Imagine yourself walking along a street in New York City, Los Angeles, Tokyo, Paris, or São Paolo. What do you see? Skyscrapers towering above crowded streets? Sprawling residential neighborhoods, tall apartment buildings, cavernous shopping malls, trendy restaurants, museums, clubs, theaters? Or traffic jams, air pollution, gang violence, crime, and run-down houses in inner-city neighborhoods? Cities can have all of these features and more. They offer some of the best and worst things in life: education and illiteracy, well-kept neighborhoods and poor ghettos, vast wealth and abject poverty. As more people move to cities from the countryside in the process called urbanization, cities become more numerous, populous, and powerful. As we first learned in Unit 2, worldwide, there are already 11 metacities, which are cities with more than 20 million inhabitants. For example, more than 37 million people crowd together in Tokyo, which may be the largest city in the world. Metacities and megacities, cities with over 10 million inhabitants, play important roles in globalization, the process whereby peoples and economies in different parts of the world become increasingly interconnected and interdependent, a term we’ve encountered many times throughout this text. When deciding where to work or live, most people choose cities. More than half of the world’s people already live in cities, and studies show that more and more people worldwide are hoping to do just that. In developed countries such as the United States, Canada, Japan, and those in western Europe, 80 percent or more of the population is urban. In 2018, roughly 84 percent of Americans lived in urban areas. This Unit focuses on cities and urban land-use patterns and processes, from the rise of the first cities to the spectacular rise of world cities as centers of trade, finance, information, and migration. In the process, we examine urban land-use patterns, the processes that shape cities, the social problems that cities experience, and the challenges facing urban sustainability. We begin by defining cities and explaining how they developed through history. Cities are a relatively new phenomenon. Imagine the 2 million years since humankind appeared on Earth as a 24-hour day. In this analogy, settlements of more than a hundred people came about only in the last half hour. Towns and cities emerged only a few minutes ago. In general, a city is a relatively large, densely populated settlement with a much larger population than rural towns and villages. Cities serve as important commercial, governmental, and cultural hubs for their surrounding regions. The word urban, which you will see frequently throughout this Unit, means “relating to a city.” Often, cities are separated by vast expanses of sparsely populated rural areas. Urbanization refers to the movement of people from rural areas to cities, and it is a major trend in the world today. For many thousands of years, humans wandered the land as nomads. Eventually, they began to create more permanent settlements, and later some of these settlements developed into what we would call cities today. Today, the defining feature of cities is dense population concentration in relatively small areas where residents work mostly in nonagricultural activities. How did such settlements emerge? How did humans make the transition from a nomadic and rural existence to living in cities with many other people? Permanent Settlements The earliest settlements were agricultural villages, formed when humans decided to stay in one place to farm. These settlements were located adjacent to resource nodes of fertile river valleys that flooded every year, enriching the soil for productive crops. Thus, people could remain in place at the same location without having to move. The population of these agricultural villages rarely exceeded 200 people, many of them related to one another through birth or marriage. All the inhabitants were involved in food procurement—tending the fields or harvesting and preparing crops. As populations within the agricultural villages increased, cities developed, and more people became removed, both physically and psychologically, from everyday agricultural activities. Two elements were necessary for this dramatic social change: an agricultural surplus that resulted in population growth and the emergence of socioeconomic stratification. Agricultural Surplus As we learned in Unit 5, over time new and improved methods of farming made agriculture more productive. Farmers were able to produce more food than they needed for themselves and their families. This food surplus, or agricultural surplus, was essential to the creation of cities. Surplus agricultural production made it possible to support a larger population, so some villages grew bigger. In addition, some villagers could do something other than growing food, allowing them to focus on other occupations instead. For example, they might become potters, priests, or merchants. Socioeconomic Stratification Socioeconomic stratification is the structuring of society into distinct socioeconomic classes, including leadership (for instance, a government or ruling class) that exert some measure of control over goods and people. As rural villages grew, their social structure and economic transactions became more complicated. For example, potters needed to sell their pottery, farmers needed to maintain their irrigation systems, and merchants needed ways to settle disputes. As a result, these village societies needed to manage their increasingly complex relationships. Early governments evolved as some people in the village began to take charge of society and hired others to enforce the rules. As the need to store and distribute the agricultural surplus grew, different social classes developed, including wealthy and powerful rulers, well-to-do merchants and craftspeople, and the poorer classes of society. A society with these two elements—surplus food and an organized means of storing and distributing it—was prepared for urbanization. The first urban revolution refers to the agricultural and socioeconomic innovations that led to the rise of the earliest cities. The first cities appeared in distinct regions, such as Mesopotamia (the area between the Tigris and Euphrates rivers in modern-day Iraq) and the Nile River valley (Figure 44.1). Over time, cities appeared in the Indus River valley, the Yellow River valley of China, Mesoamerica, the Andean highlands and coastal areas of Peru, and West Africa. These urban hearth areas are shown in Figure 44.2. Figure 44.1 Early Mesopotamian and Egyptian cities. To which natural resource did these early cities have access? The places depicted are as follows. Sumer, from 3200 B C E, is labeled in the Arabian Desert northwest of the Persian Gulf including the cities of Uruk, Ur, and Lagash. The Akkadian Empire, from 2350 to 2300 B C E, surrounds the Sumer civilization and extends in the northwest direction along the Euphrates and Tigris rivers until the Mediterranean Sea. Mari is labeled on Euphrates and Akkad, Samarra, Ninevah, and Tell Halaf are along the Tigris. The Egyptian Old Kingdom, from 2850 to 2052 B C E, extends along the Nile from the Upper Egypt to Lower Egypt until where the Nile merges with the Mediterranean Sea. The cities of Thebes, Memphis, Giza, Heliopolis, Tanis, and Abu Simbel are labeled along the Nile river. Figure 44.2 The world’s first cities arose in six urban hearth areas. How do these urban hearth areas correspond with ancient centers of domestication in Figure 35.4? The urban hearth areas presented in the map are as follows. Mesoamerica, 1500 B C E, in the southern tip of Mexico and Guatemala, Belize, El Salvador, and Honduras. Andean Region, 2000 B C E, in the west pocket of Peru. Nile Valley, 3200 B C E, along the Nile River in Egypt. Mesopotamia, 4500 B C E, at the intersection of Turkey, Iran, and Iraq between the Tigris and Euphrates rivers. Huang Ho, 2500 B C E, along the Huang He River leading to East China Sea. Indus Valley, 3000 B C E, along the Indus River in current Pakistan. Small by current standards, Mesopotamian cities covered 0.5 to 2 square miles (1.3 to 5 square kilometers), and their populations rarely exceeded 30,000. Nevertheless, the densities within these cities could easily reach 10,000 people per square mile (4000 per square kilometer), which is comparable to the densities in many contemporary cities. Ongoing discoveries suggest that urban life appeared earlier in each of the hearth areas and that there are probably other hearth areas—in West Africa, for example. Located along the Niger River, south of Timbuktu in present-day Mali, Jenne-Jeno was occupied from around 250 b.c.e. to 1200 c.e. The floodplain of the Niger was well suited for farming, providing the people of the settlement with an ample supply of rice and grains for trade. Evidence of settlements organized into various occupations such as weaving, iron smithing, leather working, and potting are present around the urban centers. As a commercial trading center linked by the Niger River to Timbuktu, Jenne-Jeno is considered to be one of the largest trading hubs of ancient West Africa. How did early societies choose a location for the villages that eventually became cities? Two important criteria were site and situation. A site is an absolute location of a place on Earth. (If you need to review the concept of absolute location, review Module 2.) A site includes all the physical features of the location, such as terrain, harbors, or rivers. Looking at the map of urban hearth areas in Figure 44.2, we notice that most of the hearth areas are located in river valleys or, as in some areas of Mesoamerica and the Andean region, near lakes and mountain streams. Early agricultural settlements needed sources of water for their crops, and as the villages became cities, water was important not only for irrigation but also for transportation and sanitation. Given the importance of water to human life, it is not surprising that people chose to settle near sources of clean, fresh water. Situation refers to the relative location of a place or the location of a place in reference to its surrounding features, places of human activities, or its regional position with reference to other places. For example, a place may be close to agricultural villages, trade routes, sources of raw materials, or population centers. The situation of a place changes through time. For example, the river that was so important to the development and growth of a city during the industrial era may be less important during the postindustrial era, when most people work in office buildings rather than factories. Pittsburgh is a good example. Its early growth was based on both site (the confluence of three rivers) and situation (close to areas where coal and iron ore were mined, necessary inputs for manufacturing iron and steel). The city experienced several decades of decline as manufacturing operations gradually ceased. Recently, the city has seen a return to growth by reinventing itself as a center for high-tech industries, similar to those found in Silicon Valley, which do not depend on the rivers for transportation of coal and iron ore for manufacturing but do depend on an educated workforce. With several major colleges and universities such as Carnegie Mellon, University of Pittsburgh, Duquesne University and Washington & Jefferson College, Pittsburgh is well-situated to attract high-tech industries. Understanding both site and situation is important because both can contribute to urban growth and decline. Although cities originated at the hearth areas shown in Figure 44.2, cities are now found all around the world. City life diffused from the hearth areas in two different ways. First, some cities evolved spontaneously in different places across the globe, as populations grew and developed new technologies allowing for an agricultural surplus and underwent socioeconomic stratification. Second, empires and societies diffused the techniques and ideas associated with urban life to other areas, whether through trade, ocean voyages, or conquest. Diffusion of Cities in Europe There is little doubt that conquest was responsible for the diffusion of the city throughout Europe in historical times. Two well-known ancient empires that powered the diffusion of cities were the Greek Empire and the Roman Empire. Ancient Greece (represented by the city of Athens in Figure 44.3) expanded in part by spreading cities throughout the Mediterranean region. The Greeks established cities as far away as Spain, southern France, Italy, and the north shore of Africa. These cities were of modest size, rarely containing more than 5000 inhabitants, but Athens itself may have reached a population of 300,000 in the fifth century b.c.e. Figure 44.3 The diffusion of urban life. Where did the most recent cities develop? Flow lines connect cities and regions as follows. From Portugal and Spain through the Atlantic Ocean to North and South America and southern Africa. Text reads, Europeans diffuse city life through colonialism, sixteenth to nineteenth centuries. From Athens to Rome and to the United Kingdom. Text reads, Greeks and Romans introduce cities into Europe, 400 B C E to 400 C E. From Middle East to West Africa, to India, and to Brunei. Text in Africa reads, Islamic cities spread, eighth to eighteenth centuries. From India to Thailand. Text reads, Hindu cities diffuse, thirteenth century. From China to Japan and Laos. Text reads, Chinese disperse cities, 200 B C E to 400 C E. From West Russia to East Russia. Text reads, Russians introduce cities, sixteenth to twentieth centuries. The Roman Empire ultimately conquered and replaced ancient Greece and was itself centered on a city: Rome (see Figure 44.3). The Romans adopted many urban traits from the Greeks as well as the Etruscans, a society in central Italy that Rome had conquered. As the Roman Empire expanded, city life diffused farther, reaching into France, Germany, England, Spain, the Alpine countries, and parts of eastern Europe—areas that had not previously experienced urbanization. Most of these cities were, initially, military and trading outposts of the Roman Empire. Transportation lay at the heart of Roman cities. Water was transported into cities from remote regions using stone structures called aqueducts, many of which still dot the landscapes of Europe today (Figure 44.4). In addition, the far-flung parts of the Roman Empire were connected by a complicated system of roads and highways linking towns and cities. Figure 44.4 Pont du Gard, near Remoulins, France. This Roman-era aqueduct is a striking example of the infrastructure that extended throughout the Roman Empire. It was built in the first century c.e. and is one of the best-preserved aqueducts in existence. By 400 c.e., the Roman Empire had declined and so too did urban life throughout much of Europe (Figure 44.5). The Roman road system fell into disrepair, and it became much more difficult to exchange goods and ideas among cities. Cities were either destroyed or left to decay on their own, becoming small villages where a few hundred people eked out a living. Figure 44.5 Rome at its height and Rome in ruins. The image on the left, from a nineteenth-century engraving, shows Rome at its height, as seen from Mount Palatine, one of Rome’s seven hills. The image on the right, from a nineteenth-century painting, shows the ruins of the Roman Forum from the Capitoline Hill, another of Rome’s seven hills. The portrait on the left shows many beautiful buildings with columns. The portrait on the right shows wrecked buildings. Columns and arches stand aloof. Development of Cities in Spain, China, and the Americas As the Roman Empire declined, cities in other world regions thrived. For example, Spanish cities flourished as centers of learning, commerce, and governance, thanks to the North African Moorish (Islamic) rule in Iberia after the fall of the Roman Empire. In China, cities developed around traditions and beliefs, including sacred sites connecting residents to ancestors and fabulous palaces reflecting the divine order on Earth, such as the Forbidden City in Beijing (Figure 44.6). Figure 44.6 The forbidden city in Beijing, China. This center of the ancient city of Beijing remains one of the best examples of the guarded, fortress like “city within the city.” In the Americas, several indigenous cultures established urban centers before Spanish colonization in the fifteenth century. American cities were not only religious ceremonial centers but also control centers for the subjugation of surrounding conquered rural peoples. Some cities grew to an enormous size and complexity. For example, Tenochtitlán—the Aztec capital now known as Mexico City—was founded in 1325 on an island in the middle of Lake Texcoco. Residents traveled within the city by canals and to and from the mainland by three raised roads, which were reportedly wide enough to accommodate 10 horses (Figure 44.7). Figure 44.7 Pre-conquest Tenochtitlán. This image, a detail from a mural by Mexican artist Diego Rivera, shows Tenochtitlán in the background. By the time of the Spanish conquest of Mexico in 1521, Tenochtitlán had over 200,000 inhabitants, far more than any Spanish (or European) city at that time. There were palaces, gardens, fountains, and even a zoo. Aqueducts brought in fresh water, and sewage was collected for fertilizer. Bernal Díaz del Castillo, a foot soldier in the Spanish explorer Hernán Cortés’s invading army, described the city as follows: “And when we saw all those cities and villages built in the water, and other great towns built on dry land, and that straight and level causeway leading to Tenochtitlán, we were astounded. These great towns and cues [temples] and buildings rising from the water, all made of stone, seemed like an enchanted vision. . . . Indeed, some of our soldiers asked whether it was not all a dream.” The Spaniards razed it, and on its ruins they built what is today Mexico City. How do geographers explain varying regional patterns of urbanization? Urban growth comes from two sources: (1) the migration of people from rural areas to cities, and (2) natural population increase. Although the United Nations estimates that natural increase accounts for the majority of the recent growth in urban population, it was rural-to-urban migrations that historically brought millions of people into cities. Urban areas increased in size to accommodate the need for more housing and other structures, resulting in the outward expansion of cities, a process that continues today. Urbanization occurred hand in hand with industrialization and capitalism. Capitalism is an economic and political system in which a country’s trade and industry are controlled by private owners for profit rather than owned and run by the state. As industrialization took root and flourished in Europe and North America, people moved to cities from rural areas and from other countries to fill cities’ needs for a large workforce. For example, movement from the countryside to the city propelled by the pull factors of jobs and a better way of life resulted in the massive growth of Chicago in the nineteenth century and Tokyo and Mumbai in the twentieth century. Rural-to-Urban Migration in China China presents a particularly interesting example of rural-to-urban migration. Until the late 1970s, the Chinese population was mostly rural, and its communist government discouraged urbanization. Under communism, all property is publicly owned and managed. Under the logic that cities fostered class privilege, many urban Chinese were forced out of cities to work on farms during the Cultural Revolution from 1966 to 1976. State policy reform after 1978 lifted restrictions on internal migration, allowing rural Chinese to become more mobile. As a result, many Chinese abandoned a life of poverty in the countryside for a future in China’s booming industrial cities, such as Guangzhou, Shanghai, and Beijing. Today around 59 percent of China’s population is urban, and it is estimated that 70 percent of China’s population will be urban by 2025. In addition, there will be 240 Chinese cities with a population over 1 million (Figure 44.8). By 2030, China’s urban population is expected to reach a whopping 1 billion. The “urban billion” likely will have profound impacts on China’s labor market, housing, buying patterns, eating patterns, and even pop culture because urban residents often have very different tastes than rural residents. Figure 44.8 China has more than 100 cities with a population of 1 million or more. What is the spatial distribution of China’s largest cities? The cities with populations of 10 million or more are as follows. Shenzhen, Guangzhou, Chengdu, Tianjin, Beijing, and Shanghai. Cities with 5 million or more are as follows. Dongguan, Foshan, Zangzhou, Wuhan, Hangzhou, Nanjing, Quingdao, Zhengzhou, Xi’an, and Shenyang. Cities with 2 million or more are spread across the Eastern part of China. Some of them are named as follows. Lanzhou, Baotou, Taiyuan, Dalian, Nanchang, Fuzhou, Shantou, Changchun, Ningbo, Changsh, and Kumming. Urumqi is in the northwest. Cities with 1 million or more and 800,000 are spread across the Eastern part of China. None are named. Guilin at the East and Kashi at the West are two cities having 800,000 or more population. Rural-to-Urban Migration in Africa and Asia Across Africa and Asia today, large numbers of people leave their rural villages and migrate to cities in search of better economic and social opportunities. Others are forced from their lands due to civil wars, natural disaster, climate change, or seizure of their land by corrupt governments. Thus, cities can increase in size not necessarily because there is economic growth requiring urban laborers, but rather because conditions in the countryside are dismal. Unfortunately, many of the jobs in Asian and African cities are low-skilled and low-paying manufacturing and service jobs with harsh working conditions. As a result, rural-to-urban migrants often find themselves either unemployed or with jobs that barely provide a decent living (Figure 44.9). The United Nations predicts that about four-fifths of the world’s future urban growth will result from rural-to-urban migration in Africa and Asia. Figure 44.9 Beggar at an intersection in Islamabad, Pakistan. Begging in traffic is common in major cities around the world. Beggars can be recent immigrants to the. Getting around inside the city, and transporting people and goods from city to city, has been a major concern for as long as cities have existed. Innovations such as railroads, streetcars, trolleys, light rail systems, airplanes, buses, and subways have shaped and reshaped the layout and size of cities and their surroundings over time. For instance, the invention of streetcars—fixed rail systems that arose in many U.S. cities in the 1880s—led to the development of so-called streetcar suburbs. Streetcar suburbs were settlements outside of cities that had streetcar lines; the streetcars took residents into and out of the city easily, allowing urban residents to live farther away from their workplaces than they could in the past, when commuting was done by foot or horse. No innovation in transportation had a more profound impact on cities than the automobile. In the United States, Henry Ford’s mass-produced Model T made automobile ownership the norm among the middle classes, and by 1920 over a million of them had been sold. Automobiles increased personal mobility exponentially, and it has been said that Henry Ford “freed common people from the limitations of geography.” At the same time, improvements in communication systems connected cities to one another and to rural areas. In addition, innovations such as the telegraph enabled the delivery of information more rapidly than mail systems. Developed by Samuel Morse in 1844, the telegraph revolutionized long-distance communication, making it easier for businesses to operate and improving the lives of everyday Americans. Even more rapid communication, leading to more growth in businesses and the further development of cities, came with Alexander Graham Bell’s invention of the telephone, patented in 1876. Oceans and rugged terrain were no longer impediments to the diffusion of innovations and the conduct of business, and cities grew accordingly. Today, many of us communicate almost instantaneously through the Internet, but in the early days of urbanization, the invention of the telegraph and telephone were critical to the growth of cities. Today’s cities are obviously very different from the early cities of Tenochtitlán and ancient Rome. Why and in what ways have cities changed over the last six millennia? The answer to this question can be traced, in large part, to what scholars call the second urban revolution. Rather than being tied to technological innovations in agriculture, the second urban revolution arose as societies, initially those located in western Europe and later North America, became industrialized as a result of innovations in mining and manufacturing. As new technologies allowed factories to grow and new kinds of industries to develop in cities, society was transformed. The second urban revolution fundamentally reshaped cities, both spatially and in terms of their social, cultural, political, and economic functions. One social transformation brought on by industrialization was the notion of urban land as a source of income. Proximity to the city center, and therefore to the most pedestrian traffic, added economic value to the land. Other specialized locations, such as areas close to a river or harbor, or along major thoroughfares into and out of the city, also increased land value. In emerging capitalist cities, the ability to pay determined where one could live, and the city’s residential areas became segregated by economic class. The wealthy lived in the desirable neighborhoods, while those without much money were forced to live in the more disagreeable parts of the city—for example, flood-prone areas, places contaminated by factory waste, or inconvenient parts of the city where roadways and urban services were not provided easily or at all (Figure 44.10). Figure 44.10 Early industrial-era London. This painting depicts mid-nineteenth-century London, awash in industrial air and water pollution. In the ancient urban hearth areas, there was little or no separation between one’s home and one’s workplace. In most cases, work was done by the family, it centered on the home, and the workday was governed by the seasons and the rising and setting of the sun. In capitalist cities, the workplace became spatially distinct from the home, and so the laborer had to travel between them. This spatial separation of work from home, of public space from private space, both reflected and helped to shape the changing worlds of men and women. In general, men generated income from work outside the home and therefore became associated with moving about and occupying the public spaces of the city. Women, who primarily did domestic work, were considered the keepers of the private world of the home and family. They were not compensated for their labors. This association of women with private domestic space and men with public workspace deepened and became more complex over the next few hundred years. As industrialization progressed, a downtown defined by economic activity emerged, and it expanded and evolved into specialized districts. With the downtown devoted to commerce and industry, the upper classes moved to the outskirts of the city and built large houses that displayed their wealth. City governing bodies have been in place since the earliest cities formed. The early leaders took charge either by consensus or force. They were responsible for the organization of agricultural surplus, including its storage and distribution. As cities became more complex, it became necessary to manage not only the city’s infrastructure but also its water resources, sewage, and garbage disposal. Later, during the era of colonialism, European powers developed colonial cities as administrative or commercial centers. Sometimes the colonizer added colonial functions to an existing settlement if it was located on a good site and had a steady supply of labor. Colonial rulers governed the colony in much the same manner that the home country was governed, often with regulations that were inappropriate for the local culture. By the time of the Industrial Revolution, government policies regulated many different features of a city, from transportation to housing to cultural life. Policymakers were forced to confront issues of rapid growth such as slums, poverty, and public safety. To keep a city alive and growing, government policies must change as needs change. In recent years, redevelopment has become a key goal of government policies as manufacturing decreases, jobs vanish, and people move to other cities. Redevelopment refers to a set of activities and government policies intended to revitalize an area that has fallen on hard times. Redevelopment around waterways, such as canals and harbors, has revitalized many modern cities by bringing in new business opportunities, creating new cultural centers, and attracting residents to formerly empty parts of the city. Challenges remain, however. Homelessness, deindustrialization, and environmental issues are important concerns for all of the world’s major cities. In this Module, we have seen how cities evolved around the world from settlements carefully located for their site and situation to modern urban areas shaped by technological innovations and economic changes. In the next Module, we add to our understanding of urbanization by learning about the development of megacities and urban land-use practices. Agricultural surplus and socioeconomic stratification are two elements necessary for the development of cities in the first urban revolution. Early cities rose in areas known as urban hearths. Site and situation were important in the location of early cities and urban areas. Urbanization in Europe diffused through the Greek and Roman Empires. Urban centers grew independently in Spain, China, and the Americas. 44-2 Which processes influence patterns of urbanization? Rural-to-urban migration fuels the growth of cities. Innovations in transportation shaped and reshaped the layout and size of cities and their surrounding areas over time. Innovations in communication systems allowed businesses, and therefore cities, to grow. The second urban revolution was the result of industrialization and innovations in mining and manufacturing. Cities require governing bodies to manage infrastructure and provide for the needs of the population. As we saw in the previous Module, countries and subnational units such as states and provinces vary greatly in how they define cities in terms of population. In addition, cities can be categorized by size. A metropolis is a very large and densely populated city, particularly the capital or major city of a country or region, such as New York City. As a reminder, a metropolitan area (or metro area, for short) is usually quite a bit bigger than a city because it includes one or several urban areas, with their accompanying suburbs and the rural areas economically and culturally connected with the city. For example, the New York–New Jersey metropolitan area is a functionally integrated region with interconnected commerce and commuting patterns. Like cities, the size of metropolitan areas varies considerably. Let’s look at China and the United States to see how different countries define cities differently. China designates settlements with 2000 to 20,000 people as towns and those with between 20,000 and 200,000 people as small cities. A city in China is considered medium-sized if its population is between 200,000 and 500,000 and large if its population falls somewhere between 500,000 and a million. Cities with more than 1 million inhabitants are considered “super cities.” In comparison, in the United States, the U.S. Census Bureau considers any incorporated (self-governing) place that contains at least 2500 people an urban area. Starting with its 2000 census, the U.S. Census Bureau has distinguished between urbanized areas (urban areas with 50,000 people or more) and urban clusters (urban areas with fewer than 50,000 inhabitants). The U.S. Census Bureau also distinguishes between metropolitan statistical areas, each with at least one urbanized area with at least 50,000 people as its core, and micropolitan statistical areas, which have one or more urban clusters of at least 10,000 but less than 50,000 people as their cores. In 2018, there were 384 metropolitan statistical areas and 542 micropolitan statistical areas in the United States. The New York–Newark–Jersey City metropolitan area is the most populous in the country. It has almost 20 million people, and its core city, New York City, has a population of just under 9 million. The country’s smallest metropolitan statistical area, Carson City in Nevada, has only 55,400 people (Figure 45.1). For our study of urban geography, it is also helpful to distinguish between a city, a town, and a suburb. Figure 45.1 Metropolitan and micropolitan statistical areas of the United States and Puerto Rico, September 2018. Why are there large expanses with no metropolitan or micropolitan statistical areas in the central part of the United States? The Metropolitan statistical areas are in the following locations: southern central Alaska, the island of Hawaii, western Washington, western Oregon, the southern three-fourths of California, southwestern Idaho, northwestern Utah, northwest and southwest Arizona, small areas in Montana, Wyoming, and New Mexico; central Colorado, northern and central Minnesota, eastern Kansas, eastern and western Missouri, southeastern Wisconsin, northern and southwestern Illinois, southern Michigan, small areas in Oklahoma and Texas, southern Louisiana, Mississippi, and Albama along the Gulf of Mexico, most of Florida, northwestern Georgia, much of North and South Carolina, western Pennsylvania and eastern Ohio, the northeast from northern Virginia north through Maryland, Delaware, eastern Pennsylvania, southern New York, Connecticut, Rhode Island, and Massachusetts; and most of Puerto Rico. The Micropolitan statistical areas are in eastern Washington, eastern Oregon, northern California, portions of Wyoming, Utah, Colorado, and Arizona; much of Utah, and in small pockets in North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, Texas, Louisiana, Arkansas, Missouri, Iowa, Minnesota, Widsonsin, Illinois, Indiana, Kentucky, Tennessee, Mississippi, Louisiana, Alabama, Georgia, Pennsylvania, New York, Vermont, and New Hampshire. Cities, Towns, and Suburbs Towns are settlements that are smaller and less complex than cities, but they are nonetheless self-sufficient. Like cities, many towns have a central business district (CBD) and residential and nonresidential land uses such as government buildings, parks, and businesses. However, in some very small towns, often called hamlets, the CBD may have nothing more than a small grocery store, a post office, and a gas station. Suburbs are populated areas on the outskirts of a city. Generally, a suburb is a residential community with its own government (Figure 45.2). Older suburbs, often referred to as “bedroom communities,” were not self-sufficient. Residents traveled to the city or a large town for shopping and jobs. Modern suburbs are intentionally developed residential communities on the periphery of a city or large town. As we will see later, more recent suburbs may have small stores and businesses, but most residents commute to the city for jobs. Figure 45.2 Suburban development in the Dallas–Fort Worth metropolitan area. Houses on small lots clustered along gridded streets and cul-de-sacs illustrate suburban development around smaller cities in the United States. Metropolitan Statistical Areas (MSAs) In the United States, suburbs are part of metropolitan statistical areas (MSAs) defined by the United States Census Bureau. An MSA is composed of a central county plus adjacent outlying counties that are socially and economically integrated with the central county as measured by commuting volumes. Table 45.1 shows the largest United States MSAs in 2018 and their change in population from 2017. Note that the top three MSAs saw a decrease in population, while the largest population gains occurred in Texas and in Atlanta. The numbers in Table 45.1 do not tell us about population density, which we obtain by dividing total population by total land area, but they do provide information about the spatial arrangement of population around the country, pointing to areas that are gaining or losing population. A population decline of a few thousand—such as 7223 in the Los Angeles–Long Beach–Anaheim, California MSA—may not seem significant given the millions of people living there, but it points to a trend that urban planners and administrators should be aware of. Table 45.1 Change in Population of the Top 10 Metropolitan Statistical Areas (MSAs), 2018 Rank Metropolitan Statistical Area 2018 Population Change from 2017 1 New York–Newark–Jersey City, NY-NJ-PA 19,979,477 −19,474 2 Los Angeles–Long Beach–Anaheim, CA 13,291,486 −7,223 3 Chicago–Naperville–Elgin, IL-IN-WI 9,498,716 −22,068 4 Dallas–Fort Worth–Arlington, TX 7,539,711 +131,767 5 Houston–The Woodlands–Sugar Land, TX 6,997,384 +91,689 6 Washington–Arlington–Alexandria, DC-VA-MD-WV 6,249,950 +49,949 7 Miami–Fort Lauderdale–West Palm Beach, FL 6,198,782 +49,095 8 Philadelphia–Camden–Wilmington, PA-NJ-DE-MD 6,096,372 +17,921 9 Atlanta–Sandy Springs–Roswell, GA 5,949,951 +75,702 10 Boston–Cambridge–Newton, MA-NH 4,875,390 +30,793 Data from U.S. Census Bureau Population estimates. What are the sources of the economic and population data used to define these areas? Geographers access population data from the Population Reference Bureau, the U.S. Census Bureau, and the Population Division of the United Nations’ Department of Economic and Social Affairs. They use these data to create maps, charts, graphs, and tables to summarize and present information for urban studies. Remember, though, that all these organizations rely on each country’s government to supply the population counts, and different countries collect population data in different ways. Thus, a careful review of the data and conclusions drawn are necessary parts of any demographic research. Using data based on these varying criteria could result in misleading conclusions. Today, just over half of human beings—55 percent—live in cities. The United Nations estimates that by the year 2050 this figure will rise to 68 percent (Figure 45.3). The World Bank estimates that cities now grow by a combined total of 3 million people each week. The world will change dramatically as we become a predominantly urban people. Figure 45.3 People living in cities. What percentage of the world’s people are expected to live in cities in 2050? The hoizontal axis plots years ranging from 1950 through 2050 in increments of 10. The vertical axis plots percentages from 10 through 80 in increments of 10 on the left and urban population in billions from 0 through 7 in increments of 1 on the right. The data presented in the graph is in the following format: Year, urban population in billions, and percent of urban population living in cities. 1950: 0.7, 28. 1960: 1, 32. 1970: 1.3, 35. 1980: 1.7, 38. 1990: 2.3, 43. 2000: 2.9, 40. 2010: 3.5, 50. 2020: 4.2, 2. 2030: 5, 60. 2040: 5.7, 65. 2050: 6.4, 70. Can we determine the spatial pattern of the world’s cities and how many people live in them? Figure 45.4 shows the percentage of each nation’s population that lived in towns and cities in 2016—that is, its urbanization rate for that year. We can see that the countries of Europe, North America, Latin America, and the Caribbean have relatively high levels of urbanization, with approximately 75 percent or more of each country’s population living in urban areas. In contrast, African and Asian countries are less urbanized, with many countries in these regions having 40 percent or less of their population residing in urban areas. Figure 45.4 Urbanized population in the world. Which continent has the smallest percent of urban inhabitants? The data presented in the map are as follows. Regions having an urban population between 80 and 100 percent: United States, Greenland, Canada, Chile, Venezuela, Brazil, Uruguay, Argentina, Iceland, United Kingdom, Norway, Sweden, Finland, Denmark, Netherlands, Belgium, Luxembourg, Gabon, U.A.E, Saudi Arabia, Bahrain, Jordan, Israel, South Korea, Japan, Australia, Tasmania, and New Zealand. Regions having an urban population between 60 and 79.9 percent: Mexico, Cuba, Dominican Republic, El Salvador, Costa Rica, Panama, Colombia, Ecuador, Peru, Bolivia, Suriname, Congo, Djibouti, South Africa, Mauritania, Morocco, Algeria, Tunisia, Libya, Oman, Iran, Iraq, Lebanon, Turkey, Armenia, Spain, Portugal, France, Germany, Switzerland, Liechtenstein, Italy, Estonia, Latvia, Lithuania, Belarus, Ukraine, Romania, Bulgaria, Greece, Czech Republic, Austria, Hungary, Poland, Russia, Mongolia, North Korea, Malaysia, and Brunei. Regions having an urban population between 40 and 59.9 percent: Guatemala, Belize, Honduras, Costa Rica, Haiti, Paraguay, Guinea, Guinea-Bissau, Sierra Leone, Liberia, Cote d’Ivoire, Mali, Togo, Benin, Cameroon, Ghana, Nigeria, Equatorial Guinea, Central African Region, Democratic Republic of the Congo, Angola, Zambia, Namibia, Botswana, Somalia, Egypt, Syria, Georgia, Azerbaijan, Albania, Macedonia, Serbia, Moldova, Romania, Slovenia, Croatia, Cyprus, Turkmenistan, Kazakhstan, China, Thailand, Sumatra, Java, Indonesia, Philippines, and Timor-Leste. Regions having an urban population between 20 and 39.9 percent: Guyana, Bosnia and Herzegovina, Guinea, Burkina Faso, Chad, Sudan, Kenya, Tanzania, Madagascar, Mozambique, Zimbabwe, Swaziland, Lesotho, Burundi, Yemen, Uzbekistan, Kyrgyzstan, Afghanistan, Pakistan, India, Bhutan, Bangladesh, Burma, Laos, Vietnam, Cambodia, Regions having an urban population between 0 and 19.9 percent: Mali, Ethiopia, South Sudan, Rwanda, Uganda, Malawi, Nepal, and Papua New Guinea. The urban population in the developing world is growing rapidly. The World Bank estimates that most urban growth in the world today—over 90 percent of it—is occurring in the developing world. Seventy million people move into cities in the developing world each year. In addition, according to United Nations estimates, almost all the worldwide population growth in the next several decades will be concentrated in urban areas, with the cities of the less-developed regions accounting for most of that increase (Figure 45.5). The world’s two poorest regions, South Asia and sub-Saharan Africa, expect their urban populations to double by 2030. The reasons for this urban population growth and its uneven distribution around the world vary, as each country’s unique history and society create a different story of urban and economic development. Figure 45.5 The world’s largest cities since 1975, since 2000, and projected by 2025. Which two regions are predicted to have cities with 10 million or more inhabitants in 2025? The information presented is as follows. Since 1975: New York, Mexico City, and Tokyo. Since 2000: Los Angeles, Rio de Janeiro, Sao Paulo, Buenos Aires, Moscow, Cairo, Karachi, Mumbai, Delhi, Dhaka, Kolkata, Manila, Jakarta, Shanghai, and Osaka. Projected by 2025: Lagos, Kinshasa, Paris, Istanbul, Lahore, Chennai, Beijing, Guangzhou, and Shenzhen. With this enormous increase in the numbers of urban dwellers in the world’s less developed regions comes a large list of problems. For example, unemployment rates for migrants to the cities of the developing world are often over 50 percent, housing and infrastructure frequently cannot be built fast enough to keep pace with the growing population, and water and sewage systems can rarely handle the influx of new people. Thus, coping with the effects of rapid urbanization is one of the world’s ongoing challenges. Metacities and Megacities The most visible cities are the extraordinarily large settlements we call metacities, those with a regional population over 20 million, and megacities, those with a regional population over 10 million. The word “regional” is important here because these definitions include not only the city itself but also the surrounding metropolitan area. Figure 45.6 shows the world’s 30 largest cities, a majority of which are in the developing world. The top five metacities are Tokyo, Delhi, Shanghai, Sao Paulo, and Mexico City. The top five megacities are Cairo, Mumbai, Beijing, Dhaka, and Osaka–Kobe–Kyoto. This is a major change from 50 years ago, when the list was dominated by Western industrialized cities. Figure 45.6 Map of the world’s largest cities. Can you identify the metacities and megacities on the map? Cities with more than 30 million population: Tokyo. Cities with a population of 20 to 29.9 million: Mexico City, Sao Paulo, Cairo, Delhi, and Shanghai. Cities with a population between 15 and 19.9 million: New York, Mumbai, Karachi, Dhaka, Beijing, and Osaka. Cities with a population between 10 and 14.9 million: Los Angeles, Botota, Rio de Janiero, Buenos Aires, Kinshasa, Lagos, Paris, Istanbul, Moscow, Lahore, Bangalore, Kolkata, Shenzhen, Tianjin, Chongqing, Jakarta, and Manila. AP® Exam Tip Thanks to the acceleration of urbanization, megacities are an incredibly new spatial pattern. In 1975 there were only 3 megacities in the world, but by 2035, there are expected to be about 50! A point to remember is that metacities and megacities are classified strictly on the size of the population, not on their level of development, standard of living, or any other measure. For example, metropolitan Los Angeles, California, and Lagos, Nigeria, are both megacities, but they are very different in terms of their infrastructure and development. Los Angeles controls its growth, including what kinds of structure are built where, as well as its sanitary infrastructure. In contrast, Lagos’s government has little control over its growth as people move into the city in uncontrolled droves. It also lacks a well-developed sanitary infrastructure. The processes of suburbanization, urban sprawl, and decentralization have created several new land uses. Suburbanization, the movement of people from urban core areas to the surrounding outskirts of a city, began in the nineteenth century and was booming by the twentieth century. The first suburbs, including streetcar suburbs (see Module 44), grew close to the urban central business district (CBD), where most business took place. Suburban housing was developed with commuting in mind, at first around train lines. Because the city was easily accessible, most early suburbs were primarily residential, with few if any commercial services. People from the suburbs drove into the city for business, shopping, and entertainment. By the 1950s many people of the middle class owned a car, and so it became possible to locate housing farther from the CBD. Car ownership meant that being near existing train lines was no longer a priority. As long as roads could be built to connect these settlements to the CBD, the new automobile suburbs would be viable. The resulting pattern became known as sprawl, the tendency of cities to grow outward in an unchecked manner. Sprawl is particularly notable in automobile cities, whose size and shape are dictated by and almost require individual automobile ownership (Figure 45.7). Some U.S. cities, such as Miami, Atlanta, Las Vegas, and Phoenix, are automobile cities because their layouts are primarily oriented around cars. Figure 45.7 Aerial view of downtown Phoenix, Arizona. Phoenix is a quintessential automobile city. Note the straight streets that intersect at right angles and the fact that the city sprawls out into the surrounding desert for miles. Only with an automobile or another form of transportation such as a bus, train, or subway can an individual truly move about comfortably in such a city. The distances are simply too far to bike or walk. As suburbs grew, corporations began to decentralize their operations, shifting some of their departments or operations to “branch offices” in suburban areas, closer to their workforce. For example, banks established suburban branches and retailers began to rent space in shopping malls that provide huge parking areas for thousands of cars. In this way, functions that used to be associated with central cities dispersed away from the city center to other locations, such as an edge city. A distinctly American phenomenon, an edge city is a concentration of business, shopping, and entertainment that developed in the suburbs, outside of a city’s traditional downtown or central business district. Joel Garreau coined the term in his 1991 book, Edge City: Life on the New Frontier. Garreau explained how edge cities grew at major suburban highway interchanges throughout the United States as corporations located offices and huge retail stores close to major highways. An edge city must have five specific characteristics: Over 5 million square feet of office space Over 600,000 square feet of retail space A population that increases every morning and decreases every afternoon, indicating more jobs than homes Status as an end destination due to its businesses, entertainment, shopping, and recreation A history of not resembling a city three years prior to its establishment. An edge city that meets all of these criteria is Tysons Corner, or simply Tysons, Virginia, which is located outside Washington, DC, near the junctions of Interstates 495 and 66, and Virginia 267 (Figure 45.8) When it was established in the late 1980s, it was home to the largest retail area on the East Coast south of New York City. It has over 25 million square feet of office space, thousands of hotel rooms, over 100,000 jobs, entertainment, and recreation. The area was the site of Tysons, a farm town surrounded by peach farms and dairy farms prior to its rise as an edge city. Figure 45.8 Tysons Corner center and the surrounding major highways. Why would mall developers select the Tysons Corner site over a site along the Potomac River closer to Maryland? Tysons Corner is in Virginia, south of the Potomac River. In the middle of the map, at the intersection of State Roads 123 and 7 are Tysons Galleria and Tysons Corner Center Interstate 495, the Capital Beltway, runs north-south just east of the Galleria and Corner Center. McLean, Virginia is slightly northeast and Vienna, Virginia is slightly southwest, both along State Road 123. A Metro station is on the southeast. Why did edge cities become part of the American landscape? According to Garreau, edge cities are the third wave of development. The first wave was moving our homes into the suburbs away from our workplaces; the second wave, which took place in the 1960s and 1970s, was moving retail to where we lived, a phenomenon called the “malling of America.” The third wave in the 1980s and 1990s was moving our jobs out to where much of the population lived and shopped, creating the edge city. We should note here that in some areas, such as the New York metro area, jobs and housing are moving back into the city. Boomburbs are places with more than 100,000 residents, but they are not core cities in the metropolitan areas. Rather, they are large suburbs with their own governments. To be considered a boomburb and not just a suburb, the area must have maintained population growth of 10 percent or more in recent decades. This type of suburban city emerged in the later part of the twentieth century as a loosely connected group of large subdivisions, office parks, and retail centers such as strip malls were built around multiple highway interchanges on freeways. Over time, some boomburbs created downtown areas of their own. Boomburbs are found throughout the United States, but they are located mostly in a belt of metropolitan areas stretching from Texas to the Pacific Ocean, with nearly half of them located in California. Two key pieces are necessary for the creation of boomburbs: (1) large incorporated tracts of land and (2) fast, sustained development. The West, particularly the Southwest, has both. In 2006, five boomburbs had more than 300,000 residents. Currently, the largest boomburb is Mesa, Arizona. With an estimated population of over 508,000, it is more populous than Minneapolis (425,000) according to the U.S. Census Bureau. Boomburbs are changing. While most boomburbs do not have large downtowns, there is a shift from the sprawling suburban office parks of the early boomburbs to a more downtown like compact, mixed-use development. These mixed-use areas are created by infill development, the building of new retail, business, or residential spaces on vacant or underused parcels in already-developed areas. Many older boomburbs are adding walkable town centers that include offices, housing, mid-size hotels, restaurants, and retail establishments, often on land formerly used for other industries, such as manufacturing or shipping. Of course, these changes lead to the usual urban problems of traffic congestion and pollution, issues that have led some boomburbs to add light rail systems. An exurb is a semirural district located beyond the suburbs that is often inhabited by well-to-do families. Unlike suburbs, which lie just outside the city, exurbs are usually near farmland, beaches, or mountains. Exurbs are more spread out and less walkable than cities and many suburbs. Homeowners in suburbs have full access to the city for entertainment, restaurants, and employment opportunities within a reasonable drive of the city, but a move to the exurbs means an entirely different lifestyle, one that may be less frenetic but is much farther away from city amenities. While it is possible to live in the suburbs without a car and rely on public transportation, life without a car (or two or three) in the exurbs is difficult. Exurbs are not necessarily incorporated spaces. They might be unincorporated residential developments located in sparsely populated townships and counties with limited services. Thus the residents of exurbs must make some important decisions that suburban residents do not have to make, like where their water comes from or where their trash goes. A driving force behind the development of exurbs is technology. Technology makes it easier for people to work from home, avoiding a daily commute into the city. In addition, communications technologies make it easier for companies to operate with employees in many different locations. Innovations in automation make more goods and services, including education and health care, available farther from the city. The lure of space with many of the amenities of urban life may be irresistible for families that can afford it. The movement out of cities, particularly to exurbs 50 miles or more from a city center, may give rise to new self-contained living systems where people live, work, and play all in one area—in essence, exurbs may become the new suburbs. If people move out of the cities into the suburbs and exurbs, what will happen to the cities? And will the United States run out of land if exurbs keep expanding into farther and farther rings outside the city? Probably not, as the desire to live in and near large cities remains strong. In recent years, population has continued to grow in several major U.S. metropolitan areas, including Seattle (15.7 percent growth), San Diego (7.6 percent), and New York City (4.4 percent). Overall, though, in the United States population growth has been distributed mostly evenly: key cities grew by 5.8 percent, intermediate suburbs by 6.1 percent, and exurbs by 5.6 percent. It is difficult to see a specific pattern in the development of exurbs, except that most of the areas showing growth are located in the Sun Belt. The outlier is Denver, with a growth rate of 15.7 percent in its exurbs. As we’ve seen, the automobile had a huge impact on urban growth and the emergence of suburbs. Today, the vast number of automobiles brings about a number of challenges, including congested roads, long commutes, a lack of parking, and air pollution. Later in this Unit, we will examine these challenges to urban sustainability and some of the responses to them. Before we do that, though, in our next Module, we will discuss world cities and how they drive globalization. The definition of a city varies throughout the world. Often, cities are defined by the size of their population. Geographers use data from the Population Reference Bureau, the U.S. Census Bureau, and the United Nations, among other sources. Different countries use different methods to calculate their populations, making international comparisons difficult. 45-2 What are the spatial outcomes of urbanization in the contemporary world? Patterns of urbanized population reveal that the countries of Europe, North America, Latin America, and the Caribbean have relatively high levels of urbanization, but the nations of Africa and Asia are less urbanized. The majority of the world’s largest cities—metacities and megacities—are located in the developing world, a major change from 50 years ago. The rapid increase in urban population in the developing world has led to severe unemployment and infrastructure issues. 45-3 What are some new urban land uses and the challenges they create? The automobile has contributed to urban sprawl as cities grow outward in an unchecked manner. Some U.S. suburbs are called automobile cities due to their reliance on cars. Edge cities are concentrations of business, shopping, and entertainment that developed at major suburban highway interchanges. Boomburbs are quickly growing incorporated places that have more than 100,000 residents found principally in a belt stretching from Texas to the Pacific. Exurbs are located beyond the suburbs in a semirural unincorporated district inhabited chiefly by well-to-do families. Many of the globalizing forces we have already discussed in this book—the integration of international economies, the interaction of different peoples, and the reshaping of cultures—are centered on urban life. Some of these changes are beneficial, while others are not. In cities we see not only the benefits but also the pitfalls of globalization. In this Module, we focus on world cities, which have become the hubs of the international economy. Cities have long been the centers of the political and economic power in the world. For example, in the middle of the fourteenth century, Bergen, Norway, was established as a major world trading city on the North Sea (Figure 46.1). Bergen continued to be a major trading city throughout the sixteenth century, as it was the principal source of dried cod in Europe. With its prominence in trade came immigration from elsewhere in Europe, and the city flourished into the Industrial Revolution. Figure 46.1 Bergen, Norway. The image shows the port city of Bergen, a destination for tourists and cruise ships with its restored fifteenth-century buildings that serve as museums, shops, and marketplaces. By the sixteenth century, more cities played key roles as centers of trade or the seats of power in colonizing nations, and cities such as Bergen declined in global importance. Throughout the seventeenth and eighteenth centuries, European cities such as London, Amsterdam, Paris, and Rome were influential cities. In the nineteenth century, Berlin, Chicago, New York City, and St. Petersburg, Russia, also rose to power. As industrialization progressed, cities grew larger and became more powerful centers of decision making. Today’s world cities are the cities that have become the command and control centers of the global economy—the sites of major decisions about the world’s commercial networks and financial markets. World cities house the headquarters of multinational corporations, international financial service providers such as banks and stock exchanges, the offices of giant media companies, and important economic and business services. Some scholars have even argued that city regions may replace nation-states as key players in the world economy. The mayors of big cities are also becoming active players on the world stage, on par with heads of states. These influential cities also share certain characteristics: cultural diversity, cultural institutions such as museums and symphonies, hipness, accessibility, the ability to attract talented individuals, and (often) a dedication to environmental quality. In 1991, there were only three such cities: New York, London, and Tokyo. Today the list of world cities has expanded to include Paris, Tokyo, Hong Kong, Singapore, Los Angeles, Sydney, Berlin, and others (Figure 46.2). Figure 46.2 Top 25 world cities. How many of these cities are shown as metacities or megacities in Figure 45.6? The cities are as follows: San Francisco, Los Angeles, Toronto, Chicago, Boston, New York, Washington D C, Buenos Aires, Brussels, London, Paris, Madrid, Amsterdam, Berlin, Vienna, Barcelona, Moscow, Beijing, Shanghai, Seoul, Tokyo, Hong Kong, Singapore, Sydney, and Melbourne. Expanding on the concept of nodes as functional regions that we learned about in Unit 1, let’s think about world cities as nodes at the global scale. Nodes can be places that are connected to other cities where international action and interaction occur, not only internationally but also domestically. For example, Paris and London are capital cities and therefore exert political power over other cities in France and England, respectively. New York City is not a capital city, but it is a center of economic and political activity within the United States, as well as internationally. Economic Power and World Cities With the rise of the world city comes the rise of the global cosmopolitan class. Rather than being especially identified with one country, the global cosmopolitan population moves with ease from place to place. Ease of movement is usually possible only with wealth, and world cities are home to many wealthy individuals. The number of individuals with high net worth in a particular city indicates a spatial concentration of economic power. Though London tops the list when it comes to the concentration of high-net-worth individuals, the super-wealthy—those with over $30 million in net assets—may be found nearly worldwide but unevenly distributed. As Figure 46.3 shows, the extremely wealthy are concentrated in North America, Europe, and East Asia, with no extremely wealthy people in South America, Africa, or Australia. Figure 46.3 Leading world cities of the super-rich. What spatial patterns are shown on the map? The cities with more than 5000 such individuals are as follows. New York, Hong Kong, and Tokyo. 1000 to 5000 such individuals. Minneapolis-Saint Paul, Seattle, San Francisco, San Jose, Los Angeles, San Diego, Dallas-Fort Worth, Houston, Miami, Atlanta, Washington D C, Philadelphia, Boston, Chicago, Detroit, Toronto, Stockholm, Munich, Zurich, Paris, London, Singapore, Taipei, Seoul, Osaka, and Nagoya. Cities with fewer than 1000 such individuals: Phoenix, Moscow, and Shanghai. AP® Exam Tip The largest cities in the world are not always considered world cities. Population size, while important, is secondary to the number and strength of a city’s global economic linkages. Gated Communities The tastes and needs of the global cosmopolitan class have shaped the world city in particular ways, including the development of highly secured residential enclaves such as gated communities (Figure 46.4) that are located within the bounds of cities but are privately governed. They have their own services such as security and landscaping, their own oversight board that sets and enforces policies, and their own amenities such as clubhouses, golf courses, and swimming pools. Gated communities have walls or fences around them, use surveillance technology to track entry and exit, and restrict access through gates to those who live there or have been approved for temporary entry, such as the residents’ guests. Figure 46.4 South African gated community. This “security village” in Johannesburg is fortified with high walls, guarded gates, and electric fencing. South Africa’s well-to-do residents, concerned about urban crime, are driving a huge and growing security industry in the country. Approximately 15 percent of the housing in the United States is privately governed, though private governance is much more common for newer housing. The rise of private housing developments and gated communities can be traced to rising income inequality and fear. The wealthy in world cities have attempted to shut out the have-nots, both from their residential spaces and from their urban governance processes. Thus, in some ways, the urban wealthy have opted out of participation in the world city. World cities drive globalization through the networks and linkages in transportation services, communications systems, and business services. These connections are important in many ways, but their importance increases when disagreements arise and mediation of global processes becomes necessary. Transportation Services World cities are hubs of efficient and modern transportation services. These cities, some of which were built on major waterways, have harbors and well-developed ports that can handle container ships as well as massive cruise ships that carry thousands of tourists. In addition, all world cities have a major international airport that can handle passenger and cargo planes flying domestically and internationally. These modern airports offer a variety of amenities to waiting passengers, including high-end shops and restaurants. Railroad and highway networks not only link the airports and harbors but also allow for the transport of goods on trucks. Many world cities, such as Tokyo, have a high-speed rail system that carries people rapidly and efficiently from the international airport into and around the city and to other Japanese cities. Communications Systems In addition to being linked to one another through transportation networks, world cities have advanced communications systems that provide immediate access to information, not only for heads of state but also for the managers of transnational corporations and financial markets. Communications networks include influential media organizations that provide fast-breaking local news, international news, and information services (such as global stock market reports) to major corporations and industry. Business Services Business services such as stock exchanges, bond markets, and foreign currency markets are key features of world cities. These services serve as links to the corporate headquarters of international companies. Large international law and accounting firms provide advice and services, while powerful advertising agencies and marketing firms help corporations anticipate changes in the marketplace and in consumer tastes. It is in the world cities that we find such international organizations as the World Health Organization (WHO) in Geneva, Switzerland, and the United Nations Educational, Scientific, and Cultural Organization (UNESCO) in Paris, France. Also, world cities have large pools of talent and many employment opportunities for highly educated professionals. In this Module, we learned about world cities. Key cities have held economic and political power for centuries. Today, world cities are large, dynamic, and powerful. They drive globalization through advanced communication and transportation systems, and they are home to business services. In our next Module, we focus the regional and local scales rather than the global scale. World cities are control centers of the global economy, the sites of major decisions about the world’s global commercial and financial networks. World cities such as New York, London, and Tokyo are nodes that connect to other places where international action and interaction occur. World cities are often home to significant numbers of high-net-worth individuals. Gated communities reflect the efforts of the wealthy to insulate and protect themselves. 46-2 What are the networks and linkages that drive globalization? World cities drive globalization through networks and linkages in transportation services, communications systems, and business services. Geographers are interested in the distribution of cities based on their size and relationship to one another. An urban system is a set of interdependent cities or urban places connected by networks. Specifically, territories within a nation, state, or province are usually organized in a pattern of towns and cities plus their hinterlands. This arrangement makes up the network that carries goods, services, ideas, money, and labor around the territory. To better understand the idea of urban systems, look at the map in Figure 47.1, which shows the state of Washington. Figure 47.1 The urban system of the state of Washington. How does the spatial organization of the urban systems in the state of Washington differ between the eastern and western edges of the state? Can you identify second- and third-order settlements on the map? The map shows the state of Washington and the northernmost part of Oregon. Built-up areas are Seattle and Tacoma around Puget Sound, Spokane Valley near the eastern border with Idaho, Yakima in the south-central part of the state, and the Portland, Oregon metropolitan area. Freeways labeled are Interstate 5 running north-south near the western part of the state through Seattle and Portland, Interstate 90 runninng east-west and going through Seattle and Spokane, Interstate 82 branching off Interstate 90 in the middle of the state and running southeast, and Interstate 94 running east-west through Portland. Other than the interstates, there are few divided highways. Primary roads run along the Pacific coast, north-south in the eastern part of the state, and east-west in the central part of the state. Numerous secondary roads are also labeled. Cities of 500,000 or more are Seattle and Portland. Cities of 100,000 to 499,999 are Tacoma, Bellevue, Everett, and Spokane. Cities of 25,000 to 99,000 are Bellingham, Marysville, Lake Stevens, Kirkland, Kent, Auburn, Lacey, Vancouver, Yakima, Richland, Pasco, and Walla Walla. Numerous cities with populations of less than 25,000 are labeled throughout the state. Take note of the scale on the map as you are reviewing the spatial distribution of the urban centers. Look at the relative size and spacing of the cities and towns, and their proximity to the interstate highway. Locate the dominant city, Seattle, and the capital city, Olympia. Notice that there are several cities along Puget Sound between Seattle and Olympia that are part of an urban system, linked by major interstate highways, ports, and communication systems. Now look at the eastern side of the state and find Spokane, the largest city between Seattle and the Washington/Idaho border. The urban system around Spokane is much different from that surrounding Seattle. Spokane, on I-90, is a gateway to Washington but is surrounded by towns and small cities and agricultural and forested land rather than suburbs, boomburbs, and edge cities. Keep this map handy as we dig deeper into the topic of urban systems and central place theory. The urban hierarchy refers to a ranking of cities, with the largest and most powerful cities at the top of the hierarchy. Geographers have identified two ideas that help to explain the urban hierarchy: the rank-size rule and the primate city rule. In a model urban hierarchy, the rank-size rule states that the population of a settlement is inversely proportional to its rank in the urban hierarchy. In mathematics, the inverse of a number is 1 divided by that number. Now let’s think in terms of the urban hierarchy. City #2 in the hierarchy would have ½ the population of the #1 city. City #3 would have ⅓ the population of the #1 city, city #4 would have ¼ the population of the #1 city, and so on down the line. To use more specific numbers, if the largest settlement in the hierarchy has 8 million people, the second largest would have about ½ × 8 million = 4 million people, and the third largest would have about ⅓ × 8 million = 2.6 million people, and so on. If we make a list of settlements in a country beginning with the city with the largest population and continuing down the list to the city with the smallest population, we will find that the ranking produces a regular pattern, or a hierarchy of settlements, but it will not fit the rank-size rule exactly. Consider the data for the United States in Table 47.1. According to the U.S. Census Bureau, the largest city in the United States is New York City and the second largest is Los Angeles. As the table shows, Los Angeles’s population is a bit less than half of New York City’s. Chicago is the third largest city in the United States, and its population is about one-third New York City’s. As we go down the list of the 10 largest cities in the United States, there is a loose correlation with the rank-size rule. The table clearly shows that New York City is the largest city, but as we move down the list, there is a more even distribution of population among the cities than the rank-size rule would suggest, implying that the rank-size “rule” is more of a tendency than a rule. The rank-size pattern is more common in developed countries than in the developing world, where the urban pattern most often follows the primate city rule. If a country does not follow the rank-size distribution, then it may be more closely aligned with the primate city rule, in which the largest city has more than twice as many people as the second largest city. In other words, a primate city is much larger than any other city in a country, and it dominates the country’s economic, political, and cultural life. Lagos, Nigeria, has a population of over 8 million people and is a financial, commercial, educational center in the country (Figure 47.2). Lagos was the capital city of Nigeria until 1991, when Abuja became the capital city. The second largest city in Nigeria is Kano, with a population of 2.8 million residents. The city is an agricultural center and has a busy industrial sector as well. Thus, Lagos is the primate city in Nigeria but has less dominance over political life than previously because Abuja is now the capital city. Figure 47.2 Lagos, Nigeria. This port city is Nigeria’s largest city, and the largest city south of the Sahara. Lagos is a major financial center in Africa and has the largest and busiest seaport on the continent. Many developing countries are dominated by a primate city, often a former center of colonial power. However, primate cities are not unique to developing countries. They are also common in developed countries that were once colonial powers. For example, London, Moscow, Athens, and Paris dominate their respective countries culturally, politically, and financially. London has a population of 9.7 million, while England’s second largest city, Birmingham, has a population of only 2.4 million. In Russia, Moscow has a population of 12.4 million while St. Petersburg has a population of 5.4 million. On a smaller scale, Oslo, the capital city of Norway, has a population of 673,469. The next largest city, Bergen, has a population of 280,216 residents. Although the population numbers are considerably smaller than for its European neighbors, Norway follows the primate city rule. Countries with dominant primate cities often struggle to provide services to people who live some distance from the primate city. In developing countries where few people have automobiles or convenient transportation, accessing medical facilities or other services is difficult. In countries that follow the rank-size rule, residents have convenient access to services in midsize cities located throughout the country. Up to this point, we have focused on the great variety in city size and location around the world. How do geographers make sense of all of the seemingly random data? Central place theory is a model that attempts to understand why cities are located where they are. Central places are settlements that make certain types of products and services available to consumers, and central place theory seeks to explain how central places are organized in hierarchical systems. Central place theory is associated with Walter Christaller, a German urban geographer who first published his work on this concept in 1933. Christaller based his theory on five assumptions: (1) the surface of a region is flat with no physical barriers, such as mountains or rivers; (2) soil quality is the same everywhere; (3) population and purchasing power are evenly distributed; (4) the region has uniform transportation networks that permit direct travel from each settlement to the others; and (5) from any given place, any good or service can be sold in all directions out to a certain distance. Do some of these assumptions sound familiar? Go back to von Thünen’s model in Module 39 and identify the similarities. Christaller believed that cities are primarily economic centers whose main purpose is to distribute goods and services to people who are willing to travel certain distances to acquire them. According to Christaller, people will travel only short distances to acquire everyday low-order goods such as food and other regularly purchased household items. In contrast, people are willing to travel much longer distances to obtain specialized or costly high-order goods and services. For example, people are willing to travel a longer distance to visit a well-stocked art museum, seek the advice of a cardiologist, or attend a professional football or baseball game. These travel distances dictate the placement of settlements in the urban hierarchy, ranging from tiny hamlets and villages on one end, through towns and cities, and finally to a large central city. As Figure 47.3 shows, the shape of the service areas of central places is hexagonal (six-sided). Figure 47.3 Christaller’s hierarchy of central places shows the orderly arrangement of towns of different sizes. This model is an idealized presentation of places performing central functions. For each large central place, many smaller places are located within the larger place’s hinterland. Notice the nested hexagons surrounding each first-order place. The service areas of cities, towns, villages, and hamlets are depicted as hexagons of varying sizes. The city is centrally located and is represented by the largest hexagon. Town centers are located at the corners of the city service area hexagon, and are each surrounded by their own, smaller hexagonal service areas. Village centers are located at the corners of the town service area hexagons, and are each surrounded by their own, even smaller hexagonal service areas. Hamlets are the smallest units. Their centers are located at the corners of the village service area hexagons, and each has its own small hexagonal service area. The Hierarchy of Central Places: Place Order, Threshold, and Range As you read the following paragraphs, remember that Christaller developed his theory in Germany in the 1930s, so his ideas are now nearly 100 years old. Therefore, they reflect a time and place that are very different from today’s fast-paced and highly interconnected world. With that in mind, let’s more closely examine central place theory. Because people will travel only short distances to acquire the low-order goods that meet their everyday needs, such as a loaf of bread or a carton of milk, in Christaller’s model, there are many hamlets and villages (which Christaller called fourth-order places) and somewhat fewer towns (third-order places) located relatively close to one another. Figure 47.3 shows a good number of third- and fourth-order places, which are supported by the routine traffic in low-order goods. According to Christaller, services or businesses in these smaller urban places have a lower threshold, the number of people required to support a business. They also have a smaller range, the distance people will travel to acquire a good or service. According to central place theory, the smallest settlements in an urban system will be situated relatively close to one another because consumers throughout the countryside will not travel very far for that loaf of bread or carton of milk. In contrast, costlier and less frequent high-order purchases can only be made in cities (second-order places) and large regional cities (first-order places). Because people are willing to travel longer distances to obtain high-order goods and services, services in big cities have a larger range and a higher threshold because people do not purchase expensive high-order goods as frequently. Thus, large regional cities are farther apart from other cities of the same or similar size than the smaller villages and hamlets are. Christaller’s theory can offer some insight regarding the distribution of large urban centers in the United States today. Cities that act as international marketplaces, such as New York City, Chicago, and Los Angeles, are first-order places at the top of the urban hierarchy. They are located thousands of miles apart. Smaller cities, such as Boston, Seattle, and Atlanta, have regional importance as second-order cities. Towns within the urban hierarchy with importance at the subregional level are third-order places, while small villages and hamlets providing goods and services at the local level are fourth-order places. However, the modern urban system does not closely match the hexagonal pattern in Christaller’s theory. Central Place Theory Today How useful is central place theory today? We know that the urban landscape is ever changing. Some cities decline in importance while others rise; edge cities grow and gain consumer services, resembling a small regional city. Exurbs develop in mostly rural areas with no or minimal services. Let’s take another look at Washington in Figure 47.1 to determine whether Christaller’s assumptions hold today. First, compare the Spokane area in eastern Washington with the Seattle area in western Washington. You will see that eastern Washington is rural as compared with the more urban area in western Washington. Simply based on the map and knowledge of economic activities in the two regions of the state, we can make some assumptions about population and spending power in the two regions but cannot support Christaller’s assumption that population and spending power are evenly distributed. In terms of transportation, the map shows us that Washington has a transportation network that includes one east–west interstate, one north–south interstate, and one south-trending interstate with a mix of state highways and secondary roads. There are a limited number of small settlements along the interstates until one approaches the Seattle area. In short, we see some correspondence with central place theory for Washington state, but it is important to note that modern urban hierarchies often deviate from the model due to advances in technology, communications, and transportation. As capitalism shifts from a focus on making and selling goods and toward service and information industries, the characteristics of an ideal urban location evolve. It is no longer as critical to be located near transportation routes as it once was. An argument may be made that other sorts of networks, especially communications networks, are just as important in the rise of cities across the world today. In addition, it is worth considering whether the world’s major cities today will decline as cities with better locations for the modern economy grow in size and importance. San Francisco serves as an example. Its importance as a West Coast port city was high before the advent of container ships. But once containerized cargo became the norm starting in the 1970s, San Francisco’s piers were no longer needed and there was no room in the city to build the large holding lots needed for containers to go from port to rail. Oakland, San Francisco’s rival city just across the bay, was quick to invest in the large cranes and other equipment needed to handle containers. Oakland was also able to accommodate containerized cargo because it filled in the tracts of shallow bay lands, creating a massive area for the loading, unloading, and storage of cargo containers. As a result, San Francisco’s importance as a port city declined, and Oakland is now the second-largest West Coast port city (Figure 47.4). We have considered principles and models that help explain the distribution and size of cities. Christaller’s central place theory also helps us understand the interdependence of cities and towns. A tool that was developed to study the interaction of towns and cities is the gravity model. The gravity model is a mathematical model that attempts to predict how places will interact. In mathematical terms, the equation for the gravity model is the multiplication of the two populations divided by the square of the distance between them (p1 × p2 ÷ d2). Stated simply, the gravity model suggests that the closer two places are, the more they will influence each other. As distance increases, interaction decreases. (Recall the concept of distance decay from Module 1.) Urban planners sometimes use the gravity model to study migration and to plan transportation systems. For instance, New York City and the New Jersey metro region are separated only by a river. The two areas are highly interconnected, with many New Jerseyans working in New York City, and vice versa. As the price of housing in New York City continues to increase beyond the budgets of many workers, more people move to New Jersey, which means the need for additional public transportation between the two locations. However, cities or regions do not need to be in close geographic proximity to have a great deal of interaction. For example, the gravity model explains why New York City and Los Angeles have a great deal of interaction even though they are on opposite sides of the country. This conclusion is based on the complicated mathematics of the gravity model, which takes into account not only the distance between two cities but also the size of each city. The gravity model is somewhat controversial. Some geographers believe that it is not a good predictive tool. Others believe that using the model for planning purposes will lead to a perpetuation or intensification of existing patterns even where these patterns are undesirable in terms of environmental issues or income equality. In many cases, changing technologies and situations make the gravity model less relevant. Distance from a store or even some services is much less important when one can order books, groceries, and even cars over the Internet for extremely rapid delivery without leaving the comfort of one’s home! However, distribution and logistics are of importance. In this Module, we examined the several key concepts that help us understand the size and distribution of cities. We looked at theories and models that help to explain the patterns we see on the landscape today, though these models do not perfectly predict reality. Now that we have looked at the bigger picture of where cities are located relative to one another, we will examine in our next Module how cities are organized internally. An urban system is a set of interdependent cities or urban places. Economic functions of the urban system are distributed by networks that link the urban system. 47-2 How do the rank-size rule and the primate city rule help to explain the urban hierarchy? A primate city, which is disproportionately larger than all the other urban places in a country, dominates the country’s economic, political, and cultural life. Within an urban hierarchy, the population of a settlement is inversely proportional to its rank within the hierarchy. 47-3 What is the central place theory? Central place theory, a model constructed by Walter Christaller, seeks to explain the organization of central places. Christaller understood cities as economic centers that distribute goods and services to people who will travel a certain distance to acquire them. According to Christaller, the shape of the service areas of central places is a hexagon where a large first-order city provides high-order goods and fourth-order villages and hamlets provide lower-order goods. Services in small urban places have a lower threshold and smaller range than services at higher levels. Advances in technology, communications, and transportation have made Christaller’s model less applicable in modern times, although the model still offers useful insights. 47-4 What is the gravity model? The gravity model suggests that the closer two places are, the more they will influence each other. As distance increases, interaction decreases. The mathematics of the gravity model considers both the distance between two cities and the size of each city (p1 × p2 ÷ d2). The gravity model is less useful today due to technological advances. Four specific models help us understand the internal structure of cities in North America: the Burgess concentric zone model, the Hoyt sector model, the Harris and Ullman multiple-nuclei model, and the galactic city model. Let’s look at each of these in turn, beginning with the oldest model. E. W. Burgess developed the concentric zone model in 1924. Burgess was a sociologist who studied urban social problems at the University of Chicago. His observations that urban social problems, such as vice and crime, were concentrated in some areas but not others led him to develop a model of Chicago’s socio-spatial organization based on ecological theory. Burgess assumed that, like organisms, cities must grow, and people are almost universally able to achieve upward mobility. Burgess’s model organizes cities in five concentric zones or rings radiating outward from the center of the city: the central business district (CBD), zone of transition, zone of independent workers’ homes, middle-class residences, and the commuters’ zone (Figure 48.1). Burgess believed that growth within the city expanded in a predictable pattern. New migrants moved into the city and lived in the lowest-quality homes in the zone of transition (2), pushing longer-established groups to migrate toward the independent workers’ homes (3) and eventually the suburbs (zones 4 and 5) as individuals achieved the expected upward mobility. Figure 48.1 Generalizations of the internal structure of cities. (a) The Burgess concentric zone model. According to the Burgess model, in which zone do the city’s wealthiest people live? (b) The Hoyt sector model. Where do the wealthiest people live, according to the Hoyt sector model? (c) The Harris and Ullman multiple-nuclei model. What is the difference between the Hoyt sector model and the Harris and Ullman multiple-nuclei model? In the Burgess Concentric Zone model, the innermost circle is the Central Business District. It is depicted as a close cluster of tall buildings. The second circle is the Zone of transition. It contains buildings of varying shapes and sizes, all close to each other. The third circle is the Zone of Independent workers’ homes. These are depicted as multifamily units. The fourth circle is the Zone of middle-class residences. These are small single-family houses that are fairly close together. The fifth circle is the Commuter’s zone. These are larger single-family houses that are further apart. In the Hoyt Sector Model, the C B D is located in the middle. Zone 2, manufacturing and industry, occupies a strip that passes next to the central business district and extends outward. Zone 3, Low-income residential, radiates outward from the central business district into two narrow strips that are adjacent to Zone 2. Zone 5, high-income residential, radiates outward as a narrow strip from the central business district, away from zones 2 and 3. Zone 4, middle-income residential, consists of a circle that fills in the spaces between the other zones. The multiple-nuclei model consists of nine zones. Zone 1, the Central Business District, is centrally located. Zone 2, wholesale and light manufacturing, is located adjacent to Zone 1. Zone 3, Low-income residential, is above and below zones 1 and 2. Zone 4, middle-income residential, is the largest zone and is adjacent to zones 1 and 3. Zone 5, high-income residential, is outside Zone 4. Zone 6, heavy manufacturing, is a small area on the outskirts of zone 3. Zone 7, an outlying business district, is a small area between zones 4 and 5. Zone 8 is a residential suburb and is outside zone 5. Zone 9 is an industrial suburb and is located outside zone 6. Burgess determined that businesses would locate in the central business district, where land is expensive, because corporations and factory owners had the ability to generate income and outbid other land uses. He called zone 2 the zone of transition because it was in that zone that Burgess believed landlords allowed residential housing to deteriorate while anticipating the expansion of the CBD. Zone 2 provides the lowest-cost housing for those least able to pay the rent. Better neighborhoods of working-class citizens who have achieved some measure of stability and social mobility occupy zone 3. Middle-class families reside in the manicured suburbs of zone 4. Bigger homes on larger pieces of property are found in zone 5, or what we might today call the exurbs. When Burgess developed his model, there was little or no public transportation from the outer zone into the CBD, and the highly paid workers in zone 5 drove into the city by private car. There are several criticisms of the concentric zone model, including the criticism that it does not apply to many cities. It did, however, encourage other researchers to develop different models, one of which was the Hoyt sector model. Homer Hoyt was a land economist who viewed cities through a lens of economics rather than sociology. The Hoyt model or sector model, developed in 1939, focused on transportation and communication as the drivers of the city’s layout. Hoyt assumed that high-cost residential areas will grow outward from the CBD along major transportation and commuter routes, such as streetcars and elevated railroads (Figure 48.1). The highest-income groups live in zone 5, in new homes on large plots of land located along transportation lines that radiate outward from the center city (zone 1). Middle-income housing on smaller plots of land in suburbs clusters around the residential area of the wealthy. Manufacturing and light industry sectors extend outward from the CBD close to freight railroad lines (zone 2). Areas of low-income workers (zone 3) are located between the manufacturing sectors and middle-income sections of the city. Like the concentric zone model, the Hoyt model is marked by growth outward as higher-income inhabitants move outward from the CBD and the lower-income population moves into the newly vacated areas. In both models, expansion is outward from the central business district, though in different shapes. The Hoyt model was subject to similar criticisms as the Burgess model, and a third well-known model, the multiple-nuclei model, was developed. Two geographers, Chauncy Harris and Edward Ullman, developed the multiple-nuclei model in 1945. Harris and Ullman argued that a city’s downtown core (its CBD) was less of a focal point of the city than in previous decades. Their model, which combined features of the Burgess and Hoyt models, showed urban residential districts organized around several nodes, or nuclei, rather than one CBD (Figure 48.1). As people moved farther out from the city center and more highways were built, businesses and services established nodes away from the CBD. Harris and Ullman took these changes into consideration and built their model to fit the sprawling suburbs. Figure 48.1 shows just one possible way a city with multiple nuclei could be arranged. In any multi-nuclei city, there are more zones than in the Burgess and Hoyt models. Each of the different zones, or nodes, has separate functions, and each node developed independently because of these separate functions. In the example in Figure 48.1, an outlying business district labeled zone 7 is situated between zones 4 (medium-class residential) and 5 (high-class residential). It is located some distance from the central business district and offers many of the same services to inhabitants in the surrounding residential areas. Sound familiar? In 1945, the outlying business node was not as developed as the edge cities of the 1960s, but it certainly was the beginning of urban and suburban sprawl as car-based living became the norm. These rapid changes led to the development of the galactic city model. The galactic city model, also known as the peripheral model, was developed in the 1960s by various geographers, including Harris (developer of the multiple-nuclei model). In this model, the CBD remains central, but multiple shopping areas, office parks, and industrial districts are linked by a ring road or beltway. Harris based his model on Detroit, Michigan (Figure 48.2). In his model, the city is decentralized: it has a CBD of high-rise buildings surrounded by urban sprawl, including the edge cities that are located near highway interchanges for ease of access. By the mid-1970s, more Americans were employed in suburban areas than in the central cities as edge cities and the number of business parks and industrial sectors increased outside of the central city. Figure 48.2 Galactic city model: Detroit. What does this model show you about the decentralized city? The city is depicted as a circle surrounded by a ring road. It contains the following elements. 1, Central city (central business district), located in the middle of the city. 2, Suburban residential area, surrounds the C B D and fills the circle. It consists primarily of single-family houses, with a few apartment buildings. 3, Shopping malls. Two are within the suburban residential areas and one is just outside the ring road. 4, Industrial District, located just inside the ring road. 5, Office park, just outside the ring road but touching it. 6, Service Center, located on the ring road. 7, Airport complex, located some distance outside the city. 8, Employment and shopping center, located just outside the ring road but touching it. A decade later, jobs in metropolitan areas in the Sun Belt, such as Phoenix, Arizona, were in the suburbs (see Figure 45.7). Look at this aerial image and think about the models we have discussed. Can you perhaps see the original concentric zone model or the sector model? Locate the central business district in the foreground. Notice the downtown development that radiates out of the CBD and the suburban development that encroaches into the foothills that surround the desert. Indeed, an aerial view at a smaller scale would show us that high-income exurbs are developing in the hills, mountains, and desert. While we cannot determine the income level of residential areas from the photo, other sources and personal observations indicate that low-income residents live near the industrial districts located near the highways and that middle-class residential areas are located around office parks, which are located near the highway interchanges and closer to the suburbs where employees live, reducing commuting time. Few people drive into the CBD to work because most employment opportunities are found in the edge cities, industrial sections, and business parks. Think back to Module 38, where we used bid-rent theory to identify the ideal location for a farmer starting a dairy farm and market gardening operation. The principle of bid-rent is the same in urban geography: land rent (or cost) near the city center is higher than land rent farther away (Figure 48.3; also see Figure 38.3). Figure 48.3 Bid-rent and urban structure. In what sector would you expect to find homes for factory workers in this model? The city is depicted as a series of concentric circles. From the middle outward, the zones are as follows. The Central Business District, Zone of transition, Zone of independent workers’ homes, Zone of middle-class residences, and Commuter’s zone. The axes of a line graph are superimposed on the circles, with the vertex at the center of the C B D. The vertical axis is rent. The label on top of the vertical axis outside the outermost circle reads, lower and the label at the bottom inside the innermost circle reads, higher. Another label near the top of the vertical axis reads, Utility. The horizontal axis is Distance, with Near in the zone of transition and far in the Commuter’s zone. A label far to the right outside the commuter’s zone reads Accessibility. Rather than looking at perishability and cost of transportation to market, as we did when discussing the price of farmland in Module 38, here we look at the utility or usefulness of a place for specific groups and its accessibility to those groups. For example, commercial land users desire access to other commercial establishments, to markets, and to labor. People want access to their jobs, friends, family, and amenities such as restaurants and entertainment. Public institutions want to be accessible to clients. Bid-rent theory assumes that the city is on a flat plain with no physical features or barriers that affect transportation or utility (usefulness). Accessibility therefore decreases steadily with distance from the city center. Utility will also decrease with distance, but at different rates for different land uses. For instance, in the urban bid-rent model, we might find high-cost residences not only near the city center, for those who value access to the city’s amenities, but also at the edges, for those who value space and privacy and have the money to travel into the city for its amenities. High-end retail stores are also found at the edge of the city to accommodate higher-income people. Based on bid-rent theory alone, we might think that the poorest residents would end up living at the very edge of the city. We see that this is generally true in developing countries in Southeast Asia, Latin America, and sub-Saharan Africa, but in developed countries, we find wealthy residences in the farthest suburbs. The poor are generally located near the center city primarily to be near public transportation that will allow them to access their jobs. Thus, looking at both bid-rent theory and a model of a city will give us a more sophisticated understanding of urban structure. We cannot understand the structures and patterns of cities in different countries using models developed for U.S. cities. Why not? Cities in different parts of the world were created under different cultural, historical, and technological circumstances than those in the United States. The Griffin-Ford model of the Latin American city was developed by Ernst Griffin and Larry Ford in 1980 and updated by Larry Ford in 1996. In their studies of South American cities, they found that traditional elements of Latin American culture blended with the modern forces of globalization. Like the North American models, the Latin American city model is an observed representation of internal city structure. It reveals the extreme difference between areas for the privileged classes and areas for people living in extreme poverty—a feature of most South American cities. As Figure 48.4 shows, the model is a combination of concentric zones and radial sectors. In this model, the CBD has two parts: a traditional market sector that sells everyday goods and the more modern CBD sector that focuses on primary businesses, entertainment venues, and employment. The CBD remains dominant in the city due to its accessibility via public transit systems and nearby affluent areas, such as the commercial spine. The commercial spine is an extension of the CBD and is flanked by the elite residential sector (Figure 48.4). The spine ends at a mall that is also flanked by an elite residential sector. At the opposite end of the market, half of the CBD is a spine-like sector for industry that ends in an industrial park. Figure 48.4 Latin American city model. According to the Latin American city model, in which zone do the poorest people live? At the center of the model are the market and the central business district. The circular sections are as follows. Surrounding the market and C B D is the zone of maturity. It includes a small gentrification sector. The next circle is the zone of in situ acceleration, containing modest lower middle-class housing. The outermost circle is the Periferico, which is part of the zone of peripheral squatter settlements. Other sections radiate outward from the market and C B D. A narrow spine radiates from the C B D to the outermost circle and ends at a mall. From the market, a narrow industrial corridor radiates outward in the direction opposite the mall and ends in an industrial park. Starting at the C B D and radiating outward along the commercial spike and mall is a wedge-shaped elite residential sector. On both sides of the elite residential sector in the outermost circle are small middle-class residential tracts. On the same side as the industrial park, two additional wedges radiate out from the market and are called Disamenity zones. They are part of the zone of peripheral squatter settlements. The zone of maturity that rings the CBD/market center is occupied by the middle classes and contains the best housing outside of the elite sector. The zone of maturity includes a small gentrification sector. There is generally less gentrification in Latin American cities than in North American cities. The adjacent zone is the zone of in situ accretion, a transitional area between the zone of maturity and the poorest parts of the city. It contains modest housing for those in the lower middle class. The disamenity sector, a zone that offers very few services and is home to the very poor, radiates from the market through the middle-class and lower-middle-class areas. The poorest people of the city live in areas of the disamenity sector known as barrios or favelas. In extreme cases, these areas are not connected to city services, and some residents live on the street. In many Latin American cities, there is little regular law enforcement in these communities, and drug lords run the area. As shown on the model, these sectors often extend beyond the periférico (ring highway) and around the outskirts of the city. In 1967, urban geographer T. G. McGee modeled the internal organization of medium-size port cities in Southeast Asia. McGee found that the focal point of these cities was not a CBD but rather the old colonial port zone with surrounding commercial districts, the alien and Western commercial zones (Figure 48.5). Notice that there is no formal central business district in this model. The alien commercial zones were populated primarily by Chinese merchants whose residences were attached to their places of business. The mixed land-use zone surrounding the commercial zones contains various economic activities as well as some residential housing. Government activities radiate outward from the port zone, and two elite zones complete this outer spine. Figure 48.5 Southeast Asian city model. Why is there no formal central business district shown in the Southeast Asian city model? The Southeast Asian city includes concentric rings and radiating sections. The port zone is a semicircle at the edge of the city. Outisde the port is a ring of mixed land use, followed by middle-class residential, new suburbs and squatter areas, and a market gardening zone. Outisde the market gardening zone is an industrial area. On one side of the city is a wedge radiating out from the port zone. The first area is the Government Zone, followed by an older high-class residential area and a new high-class residential area. Within the mixed land use zone are three commerical areas. One is labeled Western commercial zone. It is next to the Government zone and is fully contained within the mixed land use zone. The other two are labeled Alien Commerical Zone. They both extend into the middle-class residential zone. Notice that squatter areas and new suburbs for middle-class residents are mixed. In the North American models, the poor push outward from the CBD, but this model of Southeast Asian port cities indicates that a large middle class is pushing out into the traditional outer city squatter areas. Finally, unlike the Latin American city model, the Southeast Asian model includes a market gardening zone where light agriculture takes place and a small, recently built industrial park accommodates a growing economic sector. Africa is a continent of great diversity, and this diversity includes the African cities. Islamic cities are found in North Africa and coastal East Africa where the most dominant feature is the Jami, the city’s principal mosque, in the central city (Figure 48.6). As the cities grow, smaller mosques are built toward the edge of the city. Cities in South Africa are essentially Western with elements of European and American models, including CBDs with high-rise buildings and sprawling upper-income suburbs (Figure 48.7). Because of this diversity, it is not possible to build a model that can generalize all African cities. Instead, we will look at a model for sub-Saharan African cities. Figure 48.6 The Wazir Khan mosque. The mosque is in the walled city of Lahore, capital of the Pakistani province of Punjab, Pakistan. The photo shows a panorama of the mosque’s courtyard facing the mosque’s prayer wall. Figure 48.7 City in South Africa Johannesburg skyline with Hillbrow Tower, Gauteng Province, South Africa. Cities of sub-Saharan Africa carry the imprint of European colonial powers, which laid out the urban centers in cities of the interior and in ports along the coasts. Urban geographers studying cities in sub-Saharan Africa have found that cities are likely to have three CBDs, each with distinct functions and building styles: the colonial CBD, the traditional CBD, and the market zone (Figure 48.8). The colonial CBD is a place for informal markets and a transitional business center where commerce is conducted from curbside, nonpermanent stalls or more permanent storefronts. The traditional business center is a zone of traditional one-story buildings. The market zone is open-air, informal, and essential to the city’s residents. Mixed and ethnic residential neighborhoods that are often characterized by strong ethnic identities encircle the central areas of the city, as does a mining and manufacturing zone in place since colonial times. The outer ring consists of shantytowns that are growing rapidly due to unchecked in-migration from the rural areas. Figure 48.8 Sub-Saharan Africa city model. Why does the model show three CBDs? In the center of the city are a colonial central business district, a traditional central business district, and a market zone. The innermost circle surrounding the districts is labeled Ethnic Neighbourhoods on one side and Ethnic and Mixed Neighbourhoods on the other. The next circle is the Mining and Manufacturing Zone. The outermost circle is labeled Informal Satellite Townships. Major roads and local streets radiate out from the central business district. The models discussed in this Module were popular with urban geographers throughout the mid- to late twentieth century, but due to the rapid growth of cities throughout the world, they are considered somewhat obsolete today. Still, they are useful for our studies because they show the diversity of city structure throughout the developed and developing world, and in many areas these footprints remain visible even as the city evolves and grows. In the next Module, we will look at some specifics of patterns of land use and the infrastructure of cities. The Burgess concentric zone model (1920s) shows four concentric rings surrounding the central business district. The Hoyt sector model (1930s) shows sectors radiating out from the central business district as transportation options expanded. The Harris and Ullman multiple-nuclei model shows urban residential districts organized around several nodes rather than on a primary CBD. The galactic city or peripheral models (1960s) expand on the multiple-nuclei model with the decentralization of the CBD and increasing business and residential areas to accommodate the rapidly developing suburbs. Bid-rent theory focuses on the utility of a place for specific groups and its accessibility to these groups with the assumption that both accessibility and utility decrease with distance from the city center. 48-2 What models describe the internal structure of cities in Latin America, Southeast Asia, and sub-Saharan Africa? The Latin American city model (1980s and 1990s) is a combination of concentric zones and radial sectors with a CBD divided between a traditional market and a more modern sector. Squatter settlements radiate from the market area and into the outer zone of the city. The Southeast Asian city model (1960s) shows the old colonial port as the focal point with a Western commercial zone and alien commercial zones radiating outward through a mixed-used zone. Squatter settlements are mixed with new suburban zones, indicating a rapidly advancing middle class pushing poorer people farther outside of the city. African cities are diverse with Islamic cities in the north and in coastal East Africa and Western-oriented cities in South Africa. The sub-Saharan Africa model shows three CBDs representing the colonial, traditional, marketing influences. As with other non-North American models, there is a rapidly expanding outer ring of shantytowns due to unchecked in-migration from rural areas. As we saw in Module 48, the internal organizations of cities in different regions share certain similarities. City models help us understand city structure, land-use patterns, and population density, although no model fits any city precisely. It’s important to remember, though, that most cities were unplanned. That is, people who established homes and businesses did so without considering the city’s overall structure in the future. Urban land use today continues to be driven by utility (usefulness) and accessibility (transportation technologies). Accessibility and transportation are especially important, as we saw in the sector model (see Figure 48.1b)and the multiple-nuclei model (see Figure 48.1c) that became possible with the popularity of the automobile. However, automobiles are a relatively recent invention, and they played a significant role in cities only within the last century. Early Travel to and Within Cities Early cities were compact because people mostly walked within the city. Long-distance travel was accomplished by boats, horses, or stagecoach. With industrialization, cities expanded and mass transit systems, beginning with the horse car (1850s–1880s), cable car (1873), railroads, and electric streetcar or trolley, were constructed and expanded (Figure 49.1). These transit systems controlled the development of residential and industrial areas, especially in the northeastern United States and some older cities in the U.S. interior, such as Chicago. As the transportation systems radiated outward from the city center, they provided different levels of access to areas of the expanding city. Land along the transportation systems was valuable because it offered easy accessibility to the city. Land beyond the end of the lines was less valuable because it was not as easily accessible. In general, these areas were used as agricultural land or left vacant. Figure 49.1 Electric streetcar in New Orleans. Streetcar technology has come a long way to meet the changing needs of an urban environment. Not only are streetcars becoming more efficient and aesthetically pleasing, they are also meeting the growing need to transport more people safely and effectively. The new transportation systems helped to create the socioeconomic pattern of income inequality that remains a component of modern cities. People needed a certain degree of wealth to pay for the larger single-family homes in the suburbs, meaning that the suburbs had higher average incomes than the city. Lower-income populations settled closer to the inner city, where multifamily housing was the norm and mass transit was available. While the city was home to many land uses, including heavy industry and lighter forms of business, the suburbs were home mostly to houses, and one house often looked much like all the other houses in the neighborhood. The Rise of Automotive Transportation By the 1950s, automotive transportation was the dominant means of moving people and goods, and over time the compact city expanded. Use of mass transit systems declined as people began relying on cars for transportation, though mass transit remained important to the city’s lower-income residents. By the mid-twentieth century, urban land use was much different than it had been in earlier decades. Outside of the city’s core area, lower-order commercial establishments developed around highway interchanges and major transfer points on mass transit routes. Industry and other business enterprises controlled parcels of land accessible to trade or cargo routes such as rail lines, ports, navigable rivers, and canals. Such areas also attracted a mixture of high-density apartment buildings, including higher-income complexes and lower-income apartments and slums. The least accessible—and therefore the least desirable—locations within and around the city were left for low-density residential single-family units. These patterns are consistent with bid-rent theory (see Module 48). The high cost of accessible land led to a conglomeration of department stores and other retail outlets that catered to the shopping needs of urban residents. In this way, the urban core became the highest-order central place (see Module 47). Other uses for the scarce land in the urban core were skyscrapers housing multiple or single business operations, high-end hotels, and elite apartment buildings that produced the cityscapes and skylines that we see today in large cities (Figure 49.2). Recall that population density is total population divided by total land area. A related concept is perceived density, which is the general impression of the estimated number of people present in a given area. Perceived density uses qualitative data, based on what people see or think they know about an area rather than on actual numbers. The interaction of the people and the environment is important to perceived density, as are sociocultural factors. For example, if you go to a public park at lunchtime and find that it’s crowded with people, you are likely to perceive a high population density. Likewise, when you see many high-rise apartment buildings or multistory apartment complexes, you are likely to perceive a high population density. As you travel farther from the city and see single-family homes on large parcels of land, you will perceive a much lower population density. Using our perceptions of density and our knowledge of internal city structure, we can construct a population density gradient (Figure 49.3). Notice that as distance from the CBD and multistory apartments increases, the population density decreases as we reach the suburbs with single-family homes on a single plot of land. If we were to extend the curve, we would find that population density continues to decrease as we enter areas with single-family homes on large lots of one or more acres. Those lot sizes are the result of local zoning regulations, which dictate how land can be used. Figure 49.3 Population density gradient. At what point on the population density gradient would houses be built on large-sized lots? The title reads, Population Density Curve. The vertical axis represents population density and it ranges from low to high. The horizontal axis represents distance and is labeled C B D at the left side and Suburban Residential at the right side. The curve starts at the C B D approximately one fourth of the distance from the bottom, rises sharply, then falls slowly. The following points on the curve are labeled. At the beginning, by the C B D: lower population, highly commercial. Peak of curve: Dense population, high-rise apartment complexes. Middle of graph to right side, as curve is falling: Row houses, duplexes; closely-spaced housing; and single-family housing. Applying quantitative data about New York City and one of its adjacent regions, New Jersey, to our model, we see that indeed both population density and housing density decrease as we drive farther from the city, indicating that our model of perceived population density gives us a reasonable picture of actual density within a metropolitan area (Table 49.1). Table 49.1 Housing Densities and Commuting Distance Within 50 Miles West of New York City City Population Density Residential Building Density Distance from NYC Commuting Time/Carrier New York, NY 26,403/m2 11,000.3/m2 0 miles — North Bergen, NJ 12,216/m2 4,657.8/m2 10 miles 12 to 14 minutes/train, bus, automobile Short Hills, NJ 2,433/m2 826.0/m2 23.5 miles 44 to 60 minutes/train, bus, automobile Tewksbury Township, NJ 190.1/m2 73.7/m2 47.9 miles 60 to 90 minutes/automobile, bus, train Source: Data from U.S. Census Bureau. Look at Figure 49.4 and compare it with the information for Short Hills, New Jersey, in Table 49.1. Located 25 miles from New York City, Short Hills was developed in the 1870s with private funding. It was the first planned suburban community in the United States. The owner divided 56 acres of land into half-acre plots that he sold to wealthy buyers. Understanding that wealthy people would need to commute into the city to their jobs, he established a railroad station on the existing Morris & Essex line in 1879. By 1940, Short Hills was a commuter town. Today, homes in Short Hills are valued between $600,000 and $9 million, pointing to the fact that housing close to mass transportation continues to retain value in the New York metropolitan area. The actual and perceived population density of Short Hills is one of its major attractions. Its residents value the open space, privacy, and lack of crowding that are not available in Manhattan. Figure 49.4 Population density–distance relationships for New York City, 1900 and 1940. What transportation system led to the increasing density as one moves further away from the city center between 1900 and 1940? The left vertical axis is titled Density (thousands persons per square mile) and it ranges from negative 1 to positive 6 in increments of 1. The right vertical axis is titled Density (per square mile) and the labels read, 1000, 10,000, and 100,000. The horizontal axis is titled Miles from Center and it ranges from zero to 25 in increments of 5. A line for 1900 starts at a density of 6 and zero miles from center and decreases to nearly negative 1 at 15 miles from center. A line for 1940 starts at a density of 5 and zero miles from center and ends at positive 1 at 25 miles from center. Both land value and population density decrease as one moves farther from the city center and outside the margins of the built-up area. In terms of the towns in Table 49.1, we see land values decrease the farther one moves from the CBD of New York City, partly due to a lack of convenient public transportation options in the distant towns. For example, property in North Bergen and Short Hills retains its value because both towns have a stop on the NJ Transit train line, which brings commuters into New York City quickly and efficiently. The train station is not far from any home in North Bergen or Short Hills. In contrast, the nearest public transportation into New York City is about 10–15 miles away from any location in Tewksbury. Furthermore, traveling to New York on public transportation from Tewksbury requires several stops and transfers before reaching the city, making travel time-consuming and inconvenient. As a result, unimproved land, a piece of property without housing, is less costly in Tewksbury than it is in North Bergen and Short Hills. But once a home is built on the lot, the cost to a buyer surpasses that of homes in Short Hills. Changes in Residential Building Density Population density can increase through the addition of housing units, through an increase in the number of people per housing unit, or through both. Population data for New York City since 1970 show that increases in density are largely due to increases in the numbers of residential buildings, especially since the 1990s (Figure 49.5). By 2010, residential building density was highest in Manhattan (the core of New York City), with a belt of higher building density in central Brooklyn and the west Bronx, two of New York City’s four “outer boroughs.” Clearly, people want to live as close as possible to the Manhattan and its many jobs and amenities, such as restaurants and museums. The lowest density of residential buildings was in Staten Island and eastern Queens, the other two outer boroughs, where demand for housing is lower due to the long commute time into Manhattan. Figure 49.5 Housing units and housing unit density in New York City, 1970–2010. What is the effect of the increase in housing units on New York City’s population density? The vertical axis is titled Housing Density (Thousands persons per square mile) and it ranges from 9 to 11.5 in increments of 0.5. The horizotal axis ranges from 1970 to 2010 in ten-year increments. Numbers of units and densities are as follows. 1970: 2,917,428 housing units, approximate density 9.6. 1980: 2,941,850 housing units, approximate density 9.7. 1990: 2,992,212 housing units, approximate density 9.9. 2000: 3,200,912 housing units, approximate density 10.6. 2010: 3,371,062 housing units, approximate density 11.1. Looking again at Table 49.1, we see that residential housing density drops dramatically between the city and the near suburb of North Bergen. Even more dramatic is the drop in density between the next two towns out, Short Hills and Tewksbury Township. This drop in density is partially due to local zoning practices. While homes in Short Hills are on half-acre lots, single-family homes in some parts of Tewksbury Township sit on a large 5-acre lot. However, housing density in Tewksbury Township has recently increased somewhat due to the construction of dense townhouse developments. In response, the township pursued laws and programs to preserve farmland and open space. Clearly, the people of Tewksbury Township value their low population density. Sociocultural Patterns As early as the nineteenth century, social classes in the United States began spatially separating. Low-income groups lived close to their workplace, while innovations in transportation allowed middle-income and upper-income groups to move farther from the commercial and industrial areas. The result was the spatial separation of income groups. High-income residences were located at the periphery of the city and low-income residences were in the center of the city. These residential districts were often marked by racial, ethnic, and linguistic differences, too. For example, North Bergen, which is located on the fringe of New York City, is home to a nearly equal percentage of white and Hispanic or Latino residents. Its ethnic mix is much greater than that of Short Hills and Tewksbury Township, which are predominantly white and which have higher average incomes than North Bergen. Wealthier people like Short Hills for its privacy and its access to convenient mass transit, while car ownership and the expansion of interstate highways makes Tewksbury Township more desirable than it would be without the automobile. The differences in ethnic mix in areas outside of the city line reflect important economic, political, and social trends. Historically, after 1970, U.S. cities saw a decrease in their white population, and the central city became the home of the nonwhite, poor, and aged population. During this same period, smaller cities and metropolitan areas such as Atlanta, Miami, and Albuquerque experienced rapid growth, but there, too, the increase was driven by the white population settling outside of the city center, primarily in new housing subdivisions. At the same time, industrial firms also relocated from the cities to less expensive suburbs. The result was a concentration of blue-collar lower-skilled workers living in the central city with jobs in the suburbs, and a concentration of white, highly skilled workers living in the suburbs with their higher-skilled jobs in central cities. Because the higher-skilled workers had more earning power, they were able to purchase single-family homes outside the city and commute to their jobs in the central city in their cars. Meanwhile, most blue-collar workers could not afford to relocate when their company moved to the suburbs, and they could not commute to a job outside of the bounds of public transportation. Between 2007 and about 2013, the urban core experienced a period of growth, and suburban growth stalled, due in part to a banking crisis. Unemployment was high, which made people unlikely to buy homes. However, since about 2016 there has been a resurgence of the suburb. Urban growth in the cores has slowed, and lower-density suburbs and exurbs are growing more quickly—in fact, growth has quadrupled since 2012. For example, in 2017, five times as many people moved to New York suburbs as moved into the city. The migrating groups are older retirees and millennials who cannot afford to live in central urban areas due to the high price of housing. Technological Capabilities Various technologies have shaped cities, including transportation, communication, and robotics technologies. The electric streetcar or trolley, first used in the late nineteenth century, made it possible for the middle class to spread out along major lines or radials from the center city, thus decreasing inner-city residential density. The migration of the middle class also led to more land sales and higher land values as housing was built at a rapid rate outside the city. By about 1945, automobiles were used more for commuting purposes than for recreational or social purposes. By the 1970s, more than 75 percent of all workers in metropolitan areas were using an automobile for commuting (Figure 49.6). Figure 49.6 Commuters in California stuck in congested traffic. The average American spends 2.5 work weeks in traffic per year. Boston drivers spend the most time in congested commutes, with Washington, DC, Chicago, New York City, and Los Angeles rounding out the top five. Like improved transportation, improvements in communication led to the decentralization of cities. In the twenty-first century, the rapid advances in communication and Internet technology have made it possible for businesses and highly educated white-collar employees to work remotely, thus allowing more workers to live in more remote areas of the country while earning a good income. Not all advances in technology have been good for workers. For example, the development of robotic technology has led to high unemployment levels for semiskilled factory laborers. Usually, there are few job opportunities for workers who have been displaced by robots, and there is no guarantee that those workers will find a job if they move to a more affordable location. Recently, companies have begun to sponsor retraining programs for semiskilled workers displaced by robots or factory closings. The goals are to increase the employability of low-income workers. For example, Verizon is creating retraining programs to teach digital skills to workers whose jobs are threatened by automation. Focal points will be lower-wage workers, including those who work in factories, and an emphasis on young, Black, and Hispanic workers who have not gone to college. However, the high cost of housing, and in some areas a lack of public transportation options, continues to be an issue, even for blue-collar workers with stable jobs. Cycles of Development and Infilling Cycles of development and infilling began with the expansion of the transportation systems, including streetcar or trolley systems. Recall from Module 45 that infill development is the building of new retail, business, or residential spaces on vacant or underused parcels in already-developed areas. As we’ve seen, the development and expansion of streetcar lines allowed mass migration to the suburbs. Later, rapid transit lines extended outward from the original trolley lines along the most traveled sections to service the greatest number of people. In addition to the track, stations for passenger loading and unloading were built at points along the routes. These stations eventually generated business and residential activity in their immediate vicinity. Businesses cropped up to service the needs of the commuters, who wanted to live within walking distance of the station. As transit options expanded or, in some cases, collapsed, suburban areas changed. When transit options expanded, higher-income residents had the option of moving outward to “the end of the line.” At the same time, the middle class had the opportunity to move into the residential areas vacated by the high-income group, and some lower-income workers were able to move upward into better housing that also provided access to public transit. This pattern continued with the innovation of the automobile and the development of the edge cities and downtown shopping areas that we discussed in the previous Modules. Economic restructuring and metropolitan decentralization in the decades of the 2000s have resulted in a fiscal squeeze for many metropolitan areas. A fiscal squeeze occurs when city revenues cannot keep up with increasing demands for city services and expenditure on decaying urban infrastructure (Figure 49.7). What has caused the fiscal squeeze? Figure 49.7 Broken water main. Collapsing infrastructure is an ongoing and, in some cases, dangerous problem for American cities. For several decades, cities have been losing both residential population and commercial establishments to suburban areas. As a result, the city is left with abandoned housing, a lack of jobs, vacant warehouses, derelict neighborhoods, and crumbling infrastructure. As middle- and upper-class residents move out, the city’s tax base decreases, leaving it without enough tax revenue to meet its financial obligations. More homes in the city are occupied by elderly and poor households that need city welfare services but have no income or property to be taxed. Adding to their financial struggle, governments need to support the services used by the entire metropolitan population, such as public transportation and police and fire protection. To increase their tax revenue, cities are continually working to attract or develop revenue-generating sports franchises, business and conference centers, tourist attractions, and large businesses, such as Microsoft or Amazon. However, attracting high-income people and businesses requires modern urban infrastructure such as roads, bridges, parking spaces, street lighting, clean water, and working sewer systems—again adding to the fiscal squeeze. Sometimes a city can negotiate cost-sharing arrangements with business partners, perhaps in the form of an access road or parking accommodations, but for the most part, cities need to manage their infrastructure with tax dollars, bonds, or loans. The cities must pay interest on their bonds and loans, thus spending money on interest instead of on infrastructure. In addition, to attract revenue-generating organizations, cities offer fiscal advantages such as a reduction in various taxes for a specified period of years—thus decreasing revenues and perpetuating the fiscal squeeze. By the beginning of the twenty-first century, the types of business supporting urban areas began to change. Specifically, the industrial economic base gave way to a new economy based on digital technologies. Rather than providing manufacturing jobs for blue-collar workers, cities became more invested in white-collar jobs such as those in international finance, insurance, real estate, and communications. This change resulted in more upper- and middle-class jobs and fewer jobs for unskilled and semiskilled workers. The decline of blue-collar jobs also weakened labor unions, whose worker protections and good wages had been responsible for the rise of the middle class in America. More recently there has been a return of high-income residents to center cities as more opulent high-rise and high-cost housing is constructed, such as in Seattle, San Francisco, and New York. The result has been the displacement of lower-income residents and an increase in homelessness because less affordable housing is available (Figure 49.8). Figure 49.8 Homeless tent encampment in Los Angeles, California. Skid Row in Los Angeles is home to thousands who live either on the streets or in shelters. Los Angeles has seen a 16 percent increase in homelessness since 2018 due to the lack of affordable housing. Most metropolitan areas today have seen not only an increase in the number of very rich residents and very poor residents but also greater distinctions among the socioeconomic classes in between. Instead of two groups, “rich” and “poor,” cities may have as many as six different socioeconomic groups. This phenomenon is not limited to the United States or North America but is characteristic of cities across the world. Geographer Ronald van Kempen and urban planner Peter Marcuse have outlined six residential patterns that represent the new spatial order in most globalizing cities. Table 49.2 summarizes these patterns. Table 49.2 Residential Patterns for Six Socioeconomic Groups Residential Pattern Occupiers Building Type Comments Protected enclaves High-income groups Expensive apartments or single-family homes Favorable locations Gentrified areas Young professionals Single-family homes or renovated family homes Typically inner districts of central cities Middle-class suburbs Middle- to higher-income families Single-family homes; medium- and high-rise condominium complexes Working-class neighborhoods Middle- to low-income groups Rented tenements Differentiation according to income, occupation, or ethnicity Ethnic enclaves Ethnic groups Mixed housing Chinatown; Little Italy Excluded ghettos Very poor, never employed, homeless Slums; substandard housing The premium spaces for the very wealthy and well-off middle-class are separate from spaces that are perceived as dangerous pockets of poverty. In new suburban and exurban housing developments, developers often market security features to potential buyers. These features may include gated or walled communities with monitored security systems and attendants at the entranceways. The message is simple: live here, and you won’t have to worry about crime or the unpleasant reality of poverty. Gentrification of formerly deteriorated areas of city centers attracts higher-income residents but has the negative effect of pushing lower-income people out of the neighborhood (Figure 49.9). Figure 49.9 Gentrified neighborhood: Brooklyn brownstones. A row of brownstones in Brooklyn, New York. One stands out as painted blue among a row of homes painted red. In this Module, we looked at population and housing density in the central city and suburban areas, changes in transportation systems, and the location of housing types for different economic groups. We also saw how infrastructure can shape a city and its surrounding districts, increasing or decreasing a city’s ability to attract new tax revenue. In the next Module, we will look at design and zoning practices that can improve urban areas. Factors that drive urban land use are utility and accessibility. Early mass transit systems such as the electric streetcar (trolley) controlled the development of residential and industrial areas within cities. Socioeconomic patterns developed through differential access to transportation systems in the expanding city. Zoning regulations dictate how land can be used. Low-density suburban housing increased with the popularity of the automobile. 49-2 What are the recent patterns in city infrastructure, economic base, and housing? The loss of residential population and businesses affects the financial health of a city and its ability to repair and update infrastructure. Changes in the economic base from industry to technology allow cities to attract high-income jobs and high-profile businesses. In recent decades, socioeconomic groups in metropolitan areas have tended to cluster in housing types that are specific to each group. As you learned in Module 45, urban and suburban sprawl are common features of the built environment of industrialized cities worldwide. The built environment is the human-made space in which people live, work, and engage in leisure activities on a daily basis. By the late twentieth century, public health researchers showed that the built environment and associated features, such as high levels of pollution, can adversely affect human health. They have recommended that urban planners consider the human and environmental impacts of a growing city. In response, urban planners have developed several different approaches to using land in urban areas. Today’s city planners tend to emphasize compact, walkable places. Walkable cities with mixed land use are the most sustainable form of urban living, mostly because they reduce the need for cars, which cause pollution and traffic congestion. A city design that reduces people’s dependence on cars can lower overall energy use, reduce greenhouse gas emissions, and raise the quality of life in cities. In addition, a compact city design reduces urban sprawl, creating a distinct separation between urban and rural spaces. We begin our study of these urban design initiatives by learning about smart growth policies, New Urbanism, greenbelt development, and slow-growth cities. Smart growth policies combat regional sprawl by addressing issues of population density and transportation. Smart growth focuses on environmental protection and promoting the development of compact, walkable neighborhoods near public transportation. These policies restrict sprawl at urban edges by protecting rural farmland and encouraging denser development in cities. Smart growth initiatives usually have the following goals. Mixed land use. The primary driver behind mixed land use is the interspersal of different types of development in a neighborhood, such as residential, business, and entertainment, to bring people to a neighborhood at a variety of different times. Compact design. Compact design makes more efficient use of land that is already developed by encouraging development to grow up (in the form of taller buildings) rather than out (in the form of urban sprawl). Infill development. An important part of compact design, infill development builds on unused and underutilized lands within existing development patterns (Figure 50.1). (For a review of infill development, see Modules 45 and 49.) Walkable neighborhoods. Walkable neighborhoods require mixed-use development and smart street design that makes walking practical, safe, and convenient for all to enjoy (Figure 50.2). Variety of transportation choices. High-quality public transportation choices, well-maintained roads and bridges, and safe and convenient biking and walking infrastructure are important features of smart growth policies (Figure 50.3). Range of housing opportunities and choices. Smart growth policies encourage diverse housing options by building quality housing for people and families of all life stages and income levels. The diverse housing options also foster communities with distinct identities. Preservation of the natural environment. Preservation of natural and agricultural areas is both an environmental issue and an economic issue. Such areas provide places for recreation, tourism, and agriculture. Figure 50.1 Urban infill, Dublin, Ireland. Architects designed this apartment building on a small piece of property located to the rear of an existing terrace of houses in Dublin. A minimum of four units had to be accommodated on the site to make the development economically viable. The design is meant to look like mews, a British name for a row of stables and carriage houses with living quarters above, built before motor vehicles replaced horses. Figure 50.2 A walkable neighborhood in Nashville, Tennessee. Notice the greenery that provides a buffer between the street and sidewalk. The colorful buildings and shops are situated at ground level at the sidewalk edge for easy access. Figure 50.3 Safe crosswalk for walking and biking in Ames, Iowa. Crosswalks for busy roads are painted in bright colors to highlight the crosswalk for driver and pedestrian safety. All of these goals seek to create more opportunities for healthy and satisfying urban living, but they have economic benefits for the city as well. Mixing residences with work and entertainment in a compact area promotes traffic through the area and creates a convenient, desirable, high-value real estate market that is likely to keep residents longer. City planners and officials can streamline processes for granting permits and approving plans so that development decisions are more timely, cost-effective, and predictable. At the same time, the needs of every community and the strategies to address them are best defined by the people who live and work there. Thus, encouraging community involvement is important to the success of any design that brings change to a neighborhood. While smart growth focuses on larger-scale policies that shape regional planning, New Urbanism focuses on fostering European-style cities of dense settlements, attractive architecture, and diverse housing of different types and prices within walking distance to shopping, restaurants, jobs, and public transportation. The New Urbanists advocate urban designs that emphasize a neighborhood feeling along with cultural diversity and green (environmentally sustainable) living. New Urbanism was a response to cookie-cutter developments in the suburbs and the use of large plots of agricultural land to build large single-family homes. There are 10 principles of New Urbanism, and they align with smart growth policies. These principles can be applied to projects at a wide range of scales from a single building to an entire neighborhood. Walkability. The New Urbanists suggest that most amenities (shopping, restaurants, public transit stops) should be within a 10-minute walk of home and work. They propose a pedestrian-friendly street design where buildings are close to the street, with windows, doors, and porches opening onto the neighborhood. They also believe that parking lots and garages should be hidden from view. Connectivity. Walkability is enabled by connectivity, which requires an interconnected street grid that disperses traffic and eases walking, along with a hierarchy of narrow boulevards, streets, and alleys that make walking public and pleasurable. Mixed use and diversity. New Urbanism calls for mixed-use neighborhoods, blocks, and even buildings. For example, a mixed-use building could include retail space on the ground floor with offices and/or apartments on upper floors. Diverse housing options. A range of types, sizes, and prices of homes in a neighborhood encourages diversity, helps to establish the neighborhood’s character, and provides a sense of place for homeowners. Quality architecture and urban design. New Urbanism emphasizes beauty, human comfort, and a sense of space. Mixing scale as well as use is one way to create a sense of place. For example, monumental-scale buildings may be placed near human-scale buildings (Figure 50.4). Traditional neighborhood structure. The ideal New Urbanist neighborhood has a clear center with a park and high-density development and decreasing density of mixed-use space at its edges. This ideal urban-to-rural design integrates environmental concerns with community design. Increased density. New Urbanists want to see more buildings, residences, shops, and services closer together for ease of walking. They believe that this density enables a more efficient use of services and resources while creating a more convenient, enjoyable place to live. Smart transportation. New Urbanists emphasize the importance of developing public transportation for long-distance travel. They also consider how commuters connect to public transportation, emphasizing pedestrian-friendly streets and bike paths that connect residences with stops on public transport. Sustainability. Respect for the environment is a major part of New Urbanism. The goals are energy efficiency, reduced use of nonrenewable energy sources, increased local production, more walking, and less dependence on automobiles. Quality of life. The above principles, taken together, describe the overall purpose of New Urbanism: the creation of places that provide a high quality of life. Figure 50.4 Notre-Dame de Reims (Reims Cathedral), in the city of Reims, France on the Vesle River. The cathedral serves as an example of monumental-scale architecture and human-scale architecture. (a) The entryway to the cathedral is monumental-scale. (b) The doors through which we enter are human-scaled. Our homes are human-scaled, but civic buildings often are monumental scale. Advocates of smart growth policies have much in common with the New Urbanists. Both groups support the building of new housing in urban areas and near transit centers. They also support mixed land use, diverse housing options, walkability, and transit-oriented development. A key feature of plans developed with smart growth or New Urbanism in mind is attention to the environment, with an emphasis on preserving natural spaces and beautifying urban areas. Many urban plans attempt to achieve these goals with a greenbelt, a zone of grassy, forested, or agricultural land separating urban areas. Greenbelts not only beautify an area and promote healthy lifestyles, but also promote ecological health because plants absorb carbon dioxide and other types of pollution. Because building on greenbelts is greatly restricted or completely prohibited, greenbelts also connect urban dwellers to nature and limit urban sprawl. Some greenbelts serve as agricultural centers that benefit farmers and city residents. Farmers on greenbelts don’t have to transport fresh fruits and vegetables as far, and city dwellers benefit from access to fresh produce. Economic benefits to city residents include jobs in the agriculture sector and in the tourism industry. For example, cross-country ski tours, fly-fishing groups, and hiking and birding outfitters bring tourists interested in year-round outdoor activities to the area. The idea of preserving undeveloped land in and around cities began in London in 1938, when Ebenezer Howard created the English Garden City, an open space for agriculture and food-based gardening near urban centers. Today, the greenbelt surrounding London encompasses about 1.2 million acres (485,616 hectares). The major objective of London’s greenbelt is to curb unrestricted growth of London and the neighboring towns, thus limiting sprawl. The greenbelt initiative diffused from London to other parts of the United Kingdom (Figure 50.5) and the world. In the United States, the states of Oregon, Washington, and Tennessee require their largest cities to plan greenbelts to limit sprawl, and many cites have their own zoning for greenbelts (Figure 50.6). In Canada, the cities of Ottawa, Toronto, and Vancouver require the creation of greenbelts to improve land use. Larger cities in Australia, New Zealand, and Sweden have also created greenbelts to reduce sprawl and preserve agricultural and natural environments. Following a smart growth or New Urbanist plan requires coordination between the city and the many developers and builders who want to change how urban land is used. Cities can coordinate their growth and development by updating local codes and zoning ordinances. Zoning is the classification of land according to restrictions on its use and development. It is the chief planning tool of local governments to guide the community’s future development. For example, if a parcel of land is zoned for agriculture, then the local government will need to change the zoning to permit housing construction on the property. Similarly, zoning officials will have to change a zoning classification for residential land use to allow construction of a business, such as an indoor farmers’ market. Without updating local building codes and zoning ordinances, cities may find it difficult to manage growth. Slow-growth cities are cities that change their zoning laws to decrease the rate at which the city spreads horizontally, with the goal of avoiding or slowing the negative effects of sprawl. Issaquah, Washington, a suburb of Seattle, provides an example. The town’s master plan included affordable housing and used smart growth principles, but its zoning laws were inexact. As a result, out-of-state developers built a 343-unit apartment complex that stood out so much from the rest of the city’s landscape that in 2016 the city council used the Washington State Growth Management Act to stop all further development in Issaquah. This pause allowed residents and city officials to evaluate and update building codes and zoning laws before more projects were approved. Issaquah city officials spent 21 months revamping city code, creating a design and architectural manual to guide the aesthetics of future projects right down to what colors and doors builders can use. The city also developed a plan that permitted diverse housing options in the city by changing tax laws to encourage affordable housing and to allow homeowners to build second dwellings on their property. Additional planning called for replacing single-story 1980s suburban retail space with denser mixed-use, multistory projects to accommodate growth and create a more vibrant part of the city in central Issaquah. A slow-growth approach can help cities that have limited resources. For example, some cities have stopped new development on their outskirts and in the suburbs because their municipal waste treatment facility reached its capacity. Cities can also use slow-growth policies to manage traffic flow patterns and congestion. Throughout our discussion of sustainable design initiatives, we have seen the positive outcomes for people and the environment. Residents of cities that have adopted smart growth and New Urbanist policies enjoy local amenities and a high quality of life. Such cities include Portland, Oregon; Southern Village, North Carolina; Kentlands in Gaithersburg, Maryland; and Seaside, Florida (Figure 50.7). These cities also offer their residents potential health benefits such as diminished air pollution, fewer motor vehicle accidents, and increased physical exercise, all of which may reduce health care costs and increase life expectancy. Figure 50.7 Southern Village land-use map. Southern Village is a walkable community outside Chapel Hill, North Carolina. How is Southern Village a good example of mixed land use? Where do you think the outdoor concerts might be held? The central area of Southern Village is the village core and commercial area. On one side of the core is an elementary school, day care, church, office complex, and a park and ride lot. Areas labeled high residential, primarily apartments, are on two sides. On the fourth side and extending outward are ares labeled medium residential. Open green spaces separate clusters of single-family homes. A middle school is at the far end of the village. Two tours, one for walking and one for driving, are marked on the map. In addition, designs that emphasize walkability can increase pedestrian safety through the construction of sidewalks and mixed-use neighborhoods. For example, the grammar school may be located in a residential area so that children do not have to cross any busy streets as they walk to and from school. Environmentalists praise the reduction in pollution and the preservation of land, while farming communities praise the ideal of the compact city that limits sprawl. They also appreciate the presence of greenbelts that preserve farmland and give people the right to farm. In some areas, governments offer economic incentives to developers to follow the principles of smart growth. Tax breaks and reduced environmental impact fees can motivate quality development that meets standards set by government officials and can help to improve relationships between zoning officials and developers. Positive responses to greenbelts are similar to those of smart growth and New Urbanism and have been well advertised by environmentalists, government entities, and the Greenbelt Foundation. For example, published records for the Ontario Greenbelt show that there are benefits to food and farming, the local and regional economy, and protection of the environment. There are 5500 farms in the Ontario Greenbelt that produce the highest volume of foods consumed in Ontario, including 27 percent of apples, 88 percent of peaches, and more than 85 percent of grapes. The agricultural land contributes more than $9 billion to Ontario’s economy each year. The Greenbelt also provides 161,000 jobs. Because of the effects of air and water protection, the Greenbelt saves the province about $2.6 billion a year in providing fresh drinking water and clean air. Finally, the forest of the Greenbelt is capable of removing 25,000,000 pounds of pollutants over one year. Although there are many positive responses to smart growth principles and New Urbanist design features, some communities, farmers, and developers offer stiff resistance. The following are the commonly expressed concerns about the effects of smart growth, New Urbanism, and greenbelts. Property values will decrease. Property owners and real estate developers argue that increasing the population density by building high-density housing units and commercial properties will lead to more traffic and crime, leading to lower property values. Property owners also express fear that mass transit will bring crime into their neighborhoods from areas of high crime. The amount of affordable housing will decrease. There is concern that mixed-use development with sidewalks, recreation areas, and bike paths will increase the cost of housing. Additionally, setting aside large undeveloped or underdeveloped spaces as greenbelts will drive up the cost of housing by limiting the amount of land available for development. The London Greenbelt, for example, is under pressure to make protected land available for development. Property owners will face restrictions on the use of their land. Suburban homeowners complain that laws requiring sidewalks and bike paths in residential areas deprive them of lawn space and reduce privacy. Farmers protest laws that prevent development of land designated as “open space” because it limits their ability to sell their property for development. Existing communities will be disrupted. Many people fear that mixed-use development will turn low-density, quiet, residential areas into high-density, noisy, and commercial neighborhoods. Opposition to density has produced some strange alliances. For example, wealthy city residents have joined anti-displacement tenant activists (advocates for poor and working-class residents who are at risk of losing their affordable housing to new development) to oppose high-density housing. Sometimes, even projects that include affordable housing fail as a result of protests. For example, a project in New York City that proposed a 15-story residential building on the site of a derelict garage was defeated even though half of the apartments would have been rent-subsidized. Residents of the neighborhood argued that many long-term residents did not earn enough to qualify for affordable units in the building. Boston, San Francisco, and Chicago have seen similar projects defeated. New development will cause segregation. In some areas, it is likely that low-income minority communities will be displaced to make room for high-rise, smart growth housing complexes and upscale commercial development. Concerns about these projects include the possibility of de facto segregation, racial segregation that is not supported by law but is still apparent. Such segregation may not be an intentional effort to keep people of different ethnicities apart, but rather a result of the gulf between the rich and the poor. Structures and places of historical importance will be destroyed or severely impacted. Preservationists worry about the effects of smart growth and New Urbanism on culturally important buildings and areas. For example, a smart growth development plan in New York City in the 1990s did, in fact, impact an African burial ground, and construction was halted until remains were reburied elsewhere and plans for preserving and commemorating the area were completed. The African Burial Ground National Monument is situated in the Civic Center section in Lower Manhattan (Figure 50.8). Sprawl will increase rather than decrease. Opponents of smart growth argue that it often fails to achieve its intended goal of decreased sprawl and leads instead to an increase in sprawl, congestion, pollution, traffic, and other urban problems. Figure 50.8 African Burial Ground National Monument. A sacred space in Manhattan, New York City, New York where enslaved and free Africans in early New York were buried. The monument is designed to look like a portion of a globe, with western Africa in the center. Steps and a ramp allow access. In this Module, we identified urban design initiatives such as smart growth and slow-growth cities. We also reviewed the practices of New Urbanism and greenbelt development. Finally, we reviewed the pros and cons of such initiatives. This information will help us as we continue our study of urban geography in the next Module, where we look at the challenges of change within urban areas. Smart growth policies are designed to combat regional sprawl by addressing issues of population density and transportation. New Urbanism focuses on fostering European-style cities of dense settlements, attractive architecture, and diverse housing options within walking distance to shopping, restaurants, jobs, and public transportation. Greenbelts are areas of grassy, forested, or agricultural land that separate urban areas, promote healthy lifestyles, and promote ecological health. Slow-growth cities change their zoning laws to decrease the rate at which the city spreads horizontally, with the goal of avoiding or slowing the negative effects of sprawl. 50-2 What are the positive and negative responses to urban design initiatives? Positive responses to smart growth policies point to diminished air pollution, a high quality of life, fewer motor vehicle accidents, reduced health care costs, and increased life expectancies. Negative responses to urban design initiatives include the fears that property values will decrease; affordable housing will decrease; property owners will face restrictions on land; existing communities will be disrupted; de facto segregation may occur; structures and places of historical importance will be destroyed; and sprawl will increase rather than decrease. People move constantly: into and out of cities, out to the suburbs or exurbs, or within the city. For many people, however, obtaining suitable housing is not as simple as selecting a place they can afford to rent in a neighborhood they like or, if they’re buying property, getting a mortgage loan from a bank. A mortgage is a loan that is taken out to purchase a home. Property owners, real estate companies, and banks have been known to engage in the illegal practice of housing discrimination. Sometimes they even discriminate against entire neighborhoods. Housing discrimination affects not only neighborhoods but also education and labor markets, reinforcing the cycle of poverty and intensifying the disadvantages of the poor. Discrimination has sometimes taken the form of preventing groups of people from obtaining mortgages and other types of loans. Before the civil rights movement in the 1960s, many mortgage lenders engaged in redlining, the practice of identifying high-risk neighborhoods on a city map and refusing to lend money to people who wanted to buy property in those neighborhoods (Figure 51.1). The areas identified were often predominantly black neighborhoods, usually in the inner city, with an older housing stock rented by low-income blue-collar workers. Redlining is now illegal, but it worked against minorities, female-headed households, and other vulnerable groups who lived in low-income neighborhoods. Figure 51.1 1939 Federal Housing Administration (FHA) map of Chicago. What concept do these maps show? What do the levels of security in the legend indicate? Would the use of these maps be legal today? The map’s title is Home Owner’s Loan Corporation (H O L C) “red-lining” map of Chicago, 1939. Areas are rated from first grade, or best, to fourth grade, or hazardous. A small area in the southwest corner of the city is rated first grade, or best. Small areas raged second grade, or “still desirable” are scattered throughout the south side of the city, with a small area further north along the lakefront and two small areas in the far northwest corner. Areas rated Third grade, or “definitely declining” cover much of the west side, with additional small areas throughout the south side and in the far northwest corner. Areas rated Fourth Grade, or “hazardous” cover much of the north side, wth additional pockets on the south side and in the northwest corner. Overall, nearly three fourths of the city is rated as third or fourth grade. As a result of redlining, poorer neighborhoods became more run down because property owners could not obtain home-improvement loans and prospective buyers were denied a mortgage loan. Often, properties in redlined areas fell into the hands of landlords who purchased properties at low prices and then charged as much rent as possible. Housing discrimination can also occur when real estate agents play on homeowners’ prejudices and fears. Blockbusting is a practice in which realtors persuade white homeowners in a neighborhood to sell their homes by convincing them that the neighborhood is declining due to black families moving in. The realtor then sells those houses at much higher prices to black families who are seeking better housing. Blockbusting caused white flight, the mass movement of whites to the outlying suburbs (Figure 51.2). Figure 51.2 White flight. This apartment building was abandoned and left to decay as whites fled the neighborhood. Through redlining and blockbusting, realtors and investors made large profits by triggering rapid neighborhood change based on fear and prejudice. Investors and real estate developers bought large tracts of neighborhoods at low cost and then subdivided lots and built large apartment buildings. However, they did not maintain the finished buildings, which fell into disrepair, decreasing property values even further. This process affected city governments, too. As middle- and upper-class families left the city for the suburbs, cities lost tax revenue, affecting important services such as education. Both redlining and blockbusting affect affordability, the maximum price that a buyer can afford to pay for a house or apartment. In other words, affordable property is priced in a way that allows people to buy it without taking on excessive debt. In the United States, housing affordability is measured in terms of the maximum percentage of income that a homeowner can spend to repay the mortgage loan. For example, in the 1940s the maximum mortgage payment for federally subsidized loans was set at 20 percent of the borrower’s income. This figure rose to 25 percent in 1969 and to 30 percent of income in 1981. The 30 percent threshold became the standard for mortgage loans and remains so today. As house prices continue to increase, so do monthly rents. By 2014, families were paying more than 30 percent of their household income for rent. When the costs of available housing in an area are high relative to household income, people need to make trade-offs, such as commuting long distances to jobs or sharing housing with other households, leading to overcrowding. Other choices might include reduced spending on health care, food, or education to offset high housing costs. In addition, high housing costs are associated with decreased mental health, less quality time spent between parents and children, and lower educational achievement for the children of low- and moderate-income parents. To provide some assistance for housing, the federal government provides a housing choice voucher program to assist very-low-income families, the elderly, and the disabled with affordable, decent, safe, and sanitary housing. Under the program, qualifying participants find their own housing within the city or neighborhood that meets the requirements of the program. Under the program, the cost of a security deposit is not covered, a requirement that many low-income families are unable to meet. The program is subsidized by the federal government, but the renter must pay the difference between the rent and the amount paid to the landlord by the government program. However, for many low-income and very poor people, such social programs are not within reach, and they become members of the homeless population. Astronomical rents and the low quantity of affordable housing are two primary causes of homelessness. According to the Annual Point-in-Time Count by the U.S. Department of Housing and Urban Development (HUD), there were over 552,000 homeless people in the United States on a single night in 2018. Individuals make up the highest percentage of people experiencing homelessness at 67 percent. Thirty-three percent are families with children. A recent report from the National Center for Homeless Education indicated that more than 1.5 million public school students were homeless at some point during the 2017–2018 school year, the highest number recorded in more than a decade. In addition to the lack of affordable housing, homelessness among public school students can result from natural disasters, drug addiction in their parents, and fluctuations in the local economy that leave parents unemployed. Cities struggle with solutions to affordable housing and homelessness. They attempt to preserve the existing housing stock, build “tiny houses,” and construct new apartment buildings within existing and gentrified neighborhoods, but new construction, and the repair of older existing housing, simply cannot keep up with the need (Figure 51.3). Social challenges that cities face include access to services, urban crime, environmental injustice, and the growth of squatter settlements. City governments supply such services as police protection, fire protection, and sanitation, which are available citywide. Cities also provide social services such as public welfare and participation in the federal government’s housing choice voucher programs, but access to these services can be difficult for poorer residents who are most in need. Accessibility to social services depends on three factors: (1) where the people who need the services live, (2) where the services are located, and (3) how much it costs to get to and use these services. The poor often find it difficult to access these city services, to the point that they seem unattainable. Cities attempt to provide services to low-income people by establishing social service offices in or near poorer neighborhoods, where they can deliver assistance most efficiently. However, even when a social services office is located in or near a low-income neighborhood, accessibility is not guaranteed because not everyone who qualifies for aid is aware of these services, or they do not know how or where to apply for assistance. Other times long lines discourage people from seeking assistance, or childcare is a problem. The difficulties of providing services increase as the city population grows through rural-to-urban migration and global immigration. In many areas in the United States, the failure of cities to provide adequate services for the poor results in increasing numbers of homeless people, including families with children. City policies that reduce economic, racial, and ethnic segregation can help to prevent violent crime and promote healthy development. Over the past two decades, the United States has seen a significant decline in rates of violent crime—that is, instances of murder, rape, robbery, and aggravated assault (Figure 51.4). Disadvantaged, segregated communities are disproportionally affected by high violent crime rates, and while these communities have seen the same decrease in violent crime as the rest of the nation, the data show that a city’s most violent neighborhoods typically remain the most violent even when the overall crime rate drops. Variations in levels of violent crime in neighborhoods are linked to a number of characteristics, including disadvantage, segregation, land use, and the characteristics of nearby neighborhoods. Figure 51.4 Rates of violent crime in the United States, 1995–2014. What may have been some reasons for the uptick in both violent crime and murder in the years 2006–2007? The graph’s title is Violent Crime and Murder rates in the United States, 1995 - 2015. The left vertical axis is titled Rate of violent crime (per 100,000) and it ranges from 0 to 800 in increments of 100. The right vertical axis is titled Rate of murder and manslaughter (per 100,000) and it ranges from 0 to 9 in increments of 1. The horizontal axis is titled Year and it ranges from 1995 through 2015. The violent crime rate was just under 700 per 100,000 in 1995 and decreased to approxiately 500 in 2000. It held steady until 2002, then decreased to approximately 450 in 2004 and 2005, increasing slightly to approximately 490 in 2006 and 2007. The violent crime rate decreased again from 2008 through 2011 to approximately 390. After holding steady again in 2012, it decreased slightly to approximately 375 in 2014 and 2015. The murder and manslaughter rate was approximately 8 per 100,000 in 1995. It decreased steadily to approximately 5.5 in 2000 and approximately 5.25 in 2004. There was a slight increase to approximately 5.8 in 2006 and 2007, then a gradual decrease, reaching approximately 4.5 in 2015. Studies in Los Angeles and Chicago in the early 2000s showed that neighborhoods with significant concentrations of immigrants have lower rates of violent crime. One reason for these results might be that recent immigrants have a drive to succeed and motivation to work. The Los Angeles study concludes that recent immigrants moving into a city neighborhood tend to have lower homicide rates than resident groups and their descendants born in the United States because homicide flares among people who find themselves trapped and economically interdependent—dependent upon each other or city services—not among people who are highly mobile. African Americans and Hispanics are more likely to be victims of violent crimes than are whites, though the gap has narrowed in the past decade. Similarly, low-income people are much more likely to be the victims of crime. Using crime data from 9593 neighborhoods in 91 large cities, geographers found racial inequality in the average rates of violent crime. The study, based on data from the year 2000, shows that neighborhoods consisting of more than 70 percent African American residents averaged five times as many violent crimes as predominantly white communities. Predominantly Latino neighborhoods averaged about two and a half times as many violent crimes as predominantly white neighborhoods. Geographers have also identified “hotspots” within neighborhoods, micro areas such as street corners and vacant lots with a higher incidence of violent crime. For example, one study using records from 1980 through 2008 found that fewer than 3 percent of micro places in Boston accounted for more than half of all gun violence incidents. Hotspots are linked to both opportunity for violence and social controls that reduce opportunity. Social controls are formal or informal institutions that help to maintain law and order in a place. Informal social controls, such as strong social organization within the neighborhood, and formal controls, such as the presence of law enforcement, are effective in decreasing crime in neighborhoods. Evidence suggests that the policing of hotspots seems to reduce violent crime. Violent crime rates tend to increase where public housing disappears. For example, in the 1990s, some cities attempted to enact New Urbanism ideas (see Module 50) by converting run-down public housing into mixed-use buildings with improved facilities. As a result, many public housing developments were demolished, forcing thousands of neighborhood residents to relocate. Such residential instability and forced movement have been found to be factors in violent crime. Families were provided with housing vouchers that allowed them to resettle in new mixed-income housing intended to reduce economic segregation. However, not all displaced residents were able to take advantage of this program. Officials can understand trends in urban crime by using GIS to correlate crime rates in a neighborhood with demographic and socioeconomic factors. Law enforcement organizations use GIS in their daily work in order to prevent and reduce crime by identifying hotspots. Police departments and city officials can also use the trends shown in GIS visualizations to recommend crime-preventing policies and make strategic decisions. Another problem found in cities around the world is environmental injustice, which occurs when certain groups, usually poor or recent immigrants, carry a larger share of environmental risks and hazards than wealthy, long-established groups that have the power to influence decisions about the environment. One type of environmental injustice is environmental racism, in which areas inhabited by low-income people of color are targeted for environmental contamination. For example, garbage dumps and sewage treatment plants are more likely to be located in a poor neighborhood than in a wealthy neighborhood. Environmental justice is the general term for the movement to fix environmental discrimination. The Environmental Protection Agency (EPA) defines environmental justice as the “fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies.” Environmental justice movements began in the 1980s as poor communities around the globe confronted various environmental problems that affected their communities. Activists began calling attention to the fact that native peoples, people of color, women and children, and the poor are most vulnerable to environmental hazards. These vulnerable groups are mostly excluded from institutional decision making. Even though these groups bear the least responsibility for the environmental degradation, they often bear the brunt of its consequences. According to the EPA, the highest polluting facilities in the country are disproportionately located near communities of color. For example, an 85-mile stretch of land inhabited by poor and black communities between Baton Rouge and New Orleans, Louisiana, is home to more than 150 industrial plants and refineries. For decades, toxic waste dumps, industrial waste disposal, and other unwanted land uses have been placed in poor and black communities. The city of Flint, Michigan, is an example. Like many cities that prospered with the booming automobile industry in the mid-twentieth century, Flint’s population shrank rapidly in the 1980s as automobile factories began laying people off. Many of the unemployed moved out of Flint to find jobs in new industries. Of Flint’s remaining 100,000 residents, a majority are African American, and about 45 percent live below the poverty line. Nearly one in six of the city’s homes is abandoned. In 2011, with the city near bankruptcy, it fell under state control. In 2014, in a cost-saving effort, government officials switched the Flint water supply from the Detroit city system to the cheaper Flint River. For over a century, the river had been an unofficial waste disposal site for the many local industries along its shores. In addition, the river received raw sewage from the city’s waste treatment plant, agricultural and urban runoff, and toxic chemicals from leaching landfills. The water from the river was highly contaminated and corrosive, but state and city officials did not properly treat it (Figure 51.5). As a result, lead leached out from aging pipes into thousands of homes. Flint residents voiced their concerns that the water was dark-colored, smelled bad, and tasted bad. They also reported skin rashes and hair loss, but government officials dismissed these concerns until the issue gained national attention. Ignoring the concerns of the people of Flint was clearly an act of environmental injustice. Finally, in 2016, a federal court ordered Michigan state officials and the city of Flint to provide safe drinking water. It took another year for the city and state to comply with the ruling. At this writing, although tests say the city’s water is now safe, residents still use bottled water and continue to install filters on faucets in their homes. The markers of urban poverty are common and highly visible. They include the deterioration of housing and urban infrastructure and the presence of a homeless population. Urban poverty is a global phenomenon, and most world cities have pockets of both extreme wealth and extreme poverty. In cities of the developing world, however, the combination of large numbers of migrants and widespread unemployment leads to an overwhelming need for low-rent housing in ways not often seen in cities in wealthier parts of the world. Governments have rarely been able to meet this need, so the poor are forced to build housing for themselves. A common feature of cities in the developing world is the spontaneous construction of squatter settlements. Squatter settlements, also known as favelas, barriadas, shantytowns, or simply slums, are areas of degraded, seemingly temporary, inadequate, and often illegal housing. The people living in these settlements are called squatters. Often, squatters create new “housing” with scavenged materials, such as old signs, discarded pieces of wood, and sheets of metal. In the Latin American city model discussed in Module 48, these settlements are called the disamenity sector, the very poorest parts of the city with little to no municipal law enforcement. Disamenity simply means a lack of amenities, such as fresh water, electricity, and fresh food. The United Nations defines a slum household as a group of people living together who lack one or more of the following: an adequate physical structure that protects them from extreme weather, enough living area such that no more than three people share a room, access to a sufficient amount of water, access to sanitation, and secure habitation or protection from forced eviction primarily because they do not hold tenure to the land they occupy. Land tenure is the right to own or hold property and defines the ways in which rights to that property are managed. Tenure brings a sense of security that squatters do not enjoy, and they can be evicted at any time. Squatters have become an integral part of cities in most developing countries. In greater Manila, Philippines, for instance, scholars estimate that almost half of the city’s 19 million inhabitants live in slum conditions within squatter settlements. Over 1 billion people in the world, or one out of every seven people on Earth, live in slums, and some scholars predict that this number will grow to 2 billion in the next few decades. Squatter settlements usually begin as collections of crude shacks constructed from scrap materials; gradually, they become increasingly elaborate and permanent. Paths and walkways link houses, vegetable gardens spring up, and often water and electricity are bootlegged into the area so that a common tap or electrical outlet serves several dwellings (Figure 51.6). At later stages, governments install paved roads, electricity, and sewage systems, and they typically initiate some process—usually timed with the municipal elections cycle—to grant squatters legal occupancy of squatter settlement lands. Thus, the city eventually takes most squatter settlements under its wing. These once-temporary settlements become permanent parts of the city with rights to land tenure or ownership of a small plot of land. Some former slums in Mexico City, for example, have become so established that they are now attracting the wealthy and undergoing a process of gentrification. With so many challenges to healthy growth and expansion and so many avenues for discrimination and marginalization to occur, what can cities do to ensure fair treatment and access to housing and services for all of its residents? As you learned in Module 49, zoning is a powerful tool that city governments can use to bring about change. In the 1970s, many American cities addressed the dwindling supply of affordable housing and racially motivated exclusionary zoning by passing inclusionary zoning. Inclusionary zoning (IZ), also known as inclusionary housing, refers to municipal and county planning ordinances that require a given share of new construction to be affordable for people with low to moderate incomes. In contrast, exclusionary zoning, sometimes known as “snob zoning,” attempts to keep low- to moderate-income people out of a neighborhood. It includes zoning practices like mandating minimum lot sizes, such as the 2-acre lots advocated by NIMBYs, “not in my backyard” activists who try to prevent the construction of affordable housing and other types of development, such as luxury apartment buildings or mini-malls, in their neighborhoods. One positive effect of inclusionary zoning is desegregation, where lower-income and higher-income residents live in a mixed neighborhood. Sociologists believe that when lower-income people live in a more upscale neighborhood, their chances for upward mobility improve. In addition, inclusionary zoning usually requires little or no public subsidy. Instead, it requires private developers to designate a certain percentage of units in each project as below market rate. Below market rate housing costs much less than the going, or market, rate. Housing lotteries are generally held to determine who gets to occupy these affordable units. Inclusionary zoning policies are optional in some places and mandated by law in others. Laws mandating inclusionary zoning existed in 25 U.S. states and the District of Columbia at the end of 2016. Even so, IZ remains controversial and often generates lawsuits. For example, in 1975 and again in 1983, there was backlash from municipalities, homeowners, and lawmakers when the New Jersey Supreme Court mandated IZ. The court ruled that zoning regulations that prevent the construction of affordable housing are unconstitutional, and it ordered all New Jersey municipalities to plan, zone for, and take action to provide their “fair share” of affordable housing. A common criticism of IZ is that it prevents the development of high-value housing, limits the housing supply, and raises the overall price of existing homes. However, a study by the National Housing Conference’s Center for Housing Policy found that inclusionary zoning policies have not led to significant declines in overall house production or to higher housing prices. Furthermore, antipoverty advocates have suggested that inclusionary zoning can provide a substantial socioeconomic uplift for the disadvantaged. These advocates also criticize the inability of IZ policies to generate a large amount of housing for very-low-income people. Responses to economic and social challenges are not always mandated by government agencies. Overall, there has been an uptick in urban agriculture and local food movements globally. Nonprofit organizations teach people to grow food and understand how their food choices affect their health and the environment. Many of these food-growing projects are designed to increase the availability of healthy vegetables in low-income urban communities. Others produce vegetables in the city for sale in the city. For example, Montréal’s Lufa Farms built the world’s first privately owned commercial rooftop greenhouse, which supplies Montréal-grown food to city residents year-round. Despite the common view of cities as concrete jungles, there are many ways to grow food in urban spaces. For example, some Canadian cities sponsor urban fruit gleaning projects, where people harvest fruit from trees on public land such as parks or greenbelts and distribute it to low-income communities. There are also programs to show city residents how to farm in small spaces. In Saskatoon, the largest city in the Canadian province of Saskatchewan, a husband and wife team conceived of small plot intensive farming to draw attention to the idea that a backyard in the city can also be a farm. Across North America, vacant lots have been turned into community vegetable gardens where residents care for the plants in return for fresh fruits and vegetables (Figure 51.7). Figure 51.7 Repurposing abandoned spaces. Programs that turn vacant spaces into gardens to provide low-income city residents with healthy food are popular in many urban areas. Local food advocates have their detractors, however. Economists claim that a focus on the local is bad for global trade and not necessarily better for the environment. Others are concerned that small plot, locally grown food is often more expensive than the food available in supermarkets. However, it is clear that local food initiatives provide more options for low-income city residents to obtain nutritious and affordable food. Neighborhoods change in a number of ways as the residents move from one area to another, new immigrants move into housing vacated by more established groups, or people abandon neighborhoods because of a downturn in family economics. Other forms of change occur outside of a community: urban renewal and gentrification. Urban Renewal Urban renewal is large-scale redevelopment of the built environment in downtown and older inner-city neighborhoods. Typically, urban renewal projects are undertaken by the state, but more recently private developers have partnered with governments on these projects. The first urban renewal projects, in the 1950s, were driven by the post-World War II boom in the United States and by reconstruction following wartime damage in Europe. These massive public works showed state governments’ power and authority over cities. The first step in the earliest urban renewal projects was to designate a district as a slum. That designation led directly to demolition, a process that some critics called “slash and build” renewal. Residents of the area and city officials had no say in the matter. Facing public opposition, officials in the 1970s took a softer approach and emphasized smaller rehabilitation projects, neighborhood enrichment, and some amount of local empowerment. During this period, some housing was built and managed by nonprofit societies. The 1980s saw renewed massive urban change through public–private partnerships. Rather than destroying old neighborhoods and building new housing, these projects used a spectacle, such as a world’s fair or major sporting event, as the cover for major infrastructure development. Others took a softer approach. For example, in Baltimore’s Inner Harbor, waterfront development became the anchor for wider private and public redevelopment. Gentrification In Western countries, deindustrialization led to the abandonment of older industrial districts in the inner city, including waterfront areas. By the 1970s, many home buyers and commercial investors found land in the city much more affordable, and a better economic investment, than the higher-priced suburbs. The result was gentrification, the movement of upper-middle-class people into deteriorated areas of city centers. Gentrification leads to the displacement of lower-income residents as the neighborhood improves. Today, some older suburbs are also becoming gentrified, as well as some neighborhoods that began their lives as squatter settlements, such as in Mexico City (Figure 51.8). Figure 51.8 Global gentrifiers. Condesa is a neighborhood in Mexico City—probably not a place you associate with gentrification. Yet some Mexico City neighborhoods that started their lives as lower-income settlements have become targets of gentrification because of their desirable location. Gentrification often begins in an inner-city residential district, with gentrifiers moving into run-down housing or even spaces that didn’t start out as housing, such as warehouses. These places are more affordable than newer suburban housing and are often closer to workplaces or mass transit lines. The infusion of new capital into these neighborhoods usually results in higher property values, displacing existing residents who cannot afford the higher prices. The displaced residents are disproportionately poor immigrants and minorities. Their displacement opens even more housing for gentrification, and the gentrified district continues its spatial expansion. Commercial gentrification usually follows residential gentrification as middle-class newcomers introduce new patterns of consumption into the inner city. Pedestrian shopping districts with expensive boutiques and art galleries attract consumers, and higher-end bars and restaurants provide entertainment and nightlife for the gentrifiers (Figure 51.9). Gentrification in the United States has accelerated sharply, driven by the availability of underdeveloped spaces and by incentives put in place by city governments. Many city governments in the United States, faced with the abandonment of the central city by the middle class and therefore the erosion of their tax base, have enacted policies to encourage commercial and residential development in downtown areas. Some of these policies condemn target areas and transfer control of the land to a city planning agency, displacing the people who live and work there. The planning agency might locate a new civic or arts center in the target area, thus promoting private investment in the area as well (Figure 51.10). Gentrification has many benefits. It revitalizes an economically downtrodden area of the city, improves the housing stock, increases the city’s tax base, and allows people to live close to their jobs. However, gentrification also has negative consequences. It displaces lower-income people with serious consequences for the city’s social fabric. Because many of the displaced people come from disadvantaged groups, gentrification frequently contributes to racial and ethnic tensions. Displaced people are routinely forced into neighborhoods more peripheral to the city, which only adds to their disadvantages. In addition, gentrified neighborhoods usually stand in stark contrast to surrounding areas where investment has not taken place, thus creating a visible reminder of the uneven distribution of wealth within cities. The success of a gentrification project is usually measured by its appeal to an upper-middle-class clientele. Indeed, the so-called hipster gentrifiers—artists, musicians, young people, and other creative types initially attracted to these lower-cost neighborhoods—are often displaced by later waves of wealthier people who find the “cool factor” of such up-and-coming neighborhoods irresistible. Geographer Richard Campanella refers to the final wave as “bona fide gentry, including lawyers, doctors, moneyed retirees, and alpha professionals from places like Manhattan or San Francisco.” Thus, gentrification ultimately moves toward the suburban notion of residential homogeneity, eliminating what many people consider to be the great assets of urban life: diversity and heterogeneity. In the United States, how do the different levels of government work together—or not—to support a growing urban population? The U.S. federal government has explicit powers as stated in the Constitution and defined in subsequent amendments and Supreme Court decisions. States have specific powers relating to their particular geographical jurisdictions. However, the Constitution does not mention governments below the state level. Thus, there can be some confusion and conflict regarding the various roles of state, county, and city governments. In addition, neighborhood residents often want some say in governance decisions, but unless they are associations, neighborhoods do not themselves have their own governments. Take a look at a political map of your county and some neighboring counties. You may see a huge variation in the number and size of municipalities in each. How many cities are in each county? Where do the city borders end? How many towns, boroughs, and villages do you see? In addition to these political boundaries, there is another layer of government: the many different special-purpose districts, including school, fire, police, health, library, and housing districts. These special districts typically overlap with one another and with the underlying layers of other political divisions. The result is at least two specific problems: (1) problems in funding the activities of local governments and (2) organizational problems of coordinating the various local government responsibilities. Fiscal imbalance—which occurs when a government must spend more than it receives in taxes—affects all levels of government, especially in inner cities. We know that, as wealthy populations leave the deindustrializing inner cities, the income tax base disappears. The wealthier towns and suburbs can therefore raise more money through income taxes than the cities can. However, all municipalities must provide services such as education and police and fire protection. Some municipalities attempt to raise revenue by taxing retail sales, thus taxing people who spend money in the city but do not live there. Problems arise, though, when retail sales taxes are not evenly spread throughout a metropolitan area. Local businesses can be hurt when consumers choose to shop in neighboring municipalities that do not have a retail sales tax. For example, individual states in the United States may have a statewide sales tax on certain retail goods payable directly to the state government. Anyone shopping in the state will automatically pay this tax. Within that same state, county A needs to raise money and decides to enact a county retail sales tax on certain products such as shoes. In this case, people would pay two different sets of sales taxes: state and county. But neighboring county B does not enact a similar tax. Thus, people might choose to drive to county B to purchase shoes, hurting the local shoe store in county A. Driving to another county for a pair of shoes will not be of great concern to the local governments, but a mall located in county B would definitely impact businesses and the government income from retail sales taxes of county A. Increasingly, local governments are funded through money provided by federal or state governments. That is, the funds are transferred from the federal government to the state government, and on down to the county and local governments within the county. Still, the costs of providing services for a metropolitan area are often higher than the government’s tax revenue. Thus, many local governments enact taxes such as the retail sales tax described above to cover the shortfall and compete with neighboring municipalities. Organizational problems arise because rather than cooperating with each other, many local governments compete for tax-yielding economic activities through fiscal zoning. Fiscal zoning is the practice of regulating local land use to preserve and possibly enhance the local property tax base. For example, a new suburban community may permit the construction of a large regional shopping center that takes business away from commercial areas in neighboring cities and towns. In this way, the actions by one local government lead to short-term gains for itself, but possibly long-term revenue losses for the entire urban area. Fragmented local government can also lead to conflicts in providing the services that are administered by the boards of special districts. There are three kinds of special districts. (1) Districts that service an entire metropolitan area, such as a metropolitan sewer district. (2) Some districts operate as a multistate organization, such as the New York–New Jersey Port Authority (Figure 51.11). The Port Authority operates six airports in northern New Jersey and New York City, the World Trade Center in New York City, six bridges and tunnels connecting New York and New Jersey, and many other activities related to trade and transportation. (3) Finally, there are districts that provide localized services. The most numerous special districts, these are responsible for a single function, such as fire protection, housing and urban development, and education. Usually, there is no coordination in how these districts create policies regarding land-use planning, conservation, and building codes. Figure 51.11 Lower Manhattan and One World Trade Center in New York City. The World Trade Center is operated by the New York–New Jersey Port Authority, a multistate organization. The photograph is taken from Weehawken, New Jersey, looking across the Hudson River. One potential solution, though unpopular with both officials and voters, is consolidation of services. Consolidation sometimes involves centralizing services to create fewer independent districts, thus removing layers of hierarchy. For instance, instead of one building inspector for each of three small neighboring towns in a metropolitan area, the role is consolidated so that there is just one inspector serving all three towns. That inspector reports to a county or state government rather than to local officials. Neither government officials nor residents desire to give up any form of power to higher levels in the governance chain. In the end, fragmentation of services adds one more level of difficulty in providing services to the urban poor. AP® Exam Tip When writing FRQs, remember that scale and perspective will change the interpretation of an urban situation. A change to a neighborhood will be seen as positive for some community members and negative for others. Citizens, businesses, city governments, and various demographic groups will have competing priorities. In this Module, we examined several social and economic challenges facing cities today. Many of the challenges are the result of increasing population from rural-to-urban migration and immigration. Challenges include housing, squatter settlements, inclusionary zoning, and gentrification and fragmentation of government. We will conclude our study of urban geography in our next Module by learning about challenges to urban sustainability. Redlining and blockbusting are illegal forms of housing discrimination that have shaped some neighborhoods. A tight market for affordable housing leads to economic and social segregation, fewer educational opportunities for children, and homelessness. 51-2 What social challenges do cities face? Social challenges that cities face include access to services for all residents, urban crime, environmental injustice, and the growth of squatter settlements. Rural-to-urban migration and international immigration have led to larger numbers of low-income people in need of services. Rates of violent crime in the United States have declined significantly, but disadvantaged, segregated communities are still disproportionally affected by high rates of violent crime. Native peoples, people of color, women and children, and the poor are most vulnerable to environmental hazards and affected the most by environmental injustice. Squatter settlements usually begin as collections of crude shacks constructed from scrap materials; gradually, they become increasingly elaborate and permanent as cities integrate them into their borders. 51-3 What are some responses to economic and social challenges in urban areas? Inclusionary zoning (IZ) is a means of providing housing for low-income families and increasing neighborhood diversity. Local food movements increase options for obtaining nutritious and affordable food for low-income city residents. 51-4 What are the consequences of urban renewal and gentrification? Urban renewal projects are large-scale projects undertaken by the state or as public–private partnerships that often lead to demolition of old neighborhoods. Gentrification leads to the displacement of lower-income residents by higher-income residents as the neighborhood improves. Eventually, gentrified neighborhoods become expensive and available only to the wealthy. Gentrification contributes to racial and ethnic tensions and creates a visible reminder of the uneven distribution of wealth within cities. 51-5 How does government fragmentation challenge efficiency in urban governance? The many different levels of government lead to inefficiencies in governance and the provision of services. Consolidation of services involves centralizing services to create fewer independent districts, thus removing layers of hierarchy. A city’s ecological footprint, the total amount of natural resources it uses and its impact on the environment, is enormous. Urban sustainability refers to a city’s ability to use resources in a way that does not deplete them over the long term. Challenges to sustainability of our cities include suburban sprawl, the need to provide clean water and air to city residents, climate change, and the fact that cities alter natural landscapes and use large amounts of natural resources. At first glance, cities may seem totally divorced from the natural environment. What possible relationships could shiny glass office buildings, paved streets, and high-rise apartment complexes have with forests, fields, and rivers? There is a direct connection: constructing the buildings and spaces of a city means changing the natural environment by removing vegetation, flattening the ground, diverting water, even changing the way air flows around buildings that now take up what used to be open air space. What is the collective effect of a city’s changes to the natural environment? How do atmospheric conditions in cities differ from those in the countryside? If you have spent time in cities and the countryside, you may have realized that in cities, temperatures are higher, the incidence of fog and cloudiness is greater, and levels of atmospheric pollution are much higher. In addition, cities get more rainfall. Why? Cities cover large areas of land with streets, buildings, parking lots, and rooftops, so about 50 percent of the urban area is a hard surface. Rainfall is quickly carried into gutters and sewers, which means that little standing water is available for evaporation back into the atmosphere. When water evaporates, it carries heat with it to the upper atmosphere. Less evaporation means that air temperatures are higher. Moreover, cities generate enormous amounts of heat, not only from the heating systems of buildings but also from automobiles, industry, and even human bodies. The hard surfaces so prevalent in urban areas not only repel water, but also retain heat very effectively. The result is an urban heat island, a mass of warm air generated by urban building materials and human activities. The urban heat island sits over the city and causes urban temperatures to be higher than those of surrounding areas. Yearly temperature averages in cities are 3.5°F (2°C) higher than in the countryside, and during the winter, when there is more city-produced heat, the average difference can easily reach 7°F to 10°F (4°C to 5.6°C) (Figure 52.1). Such temperature changes increase the demand for energy to heat and cool buildings, contributing to increased energy costs and to the city’s ecological footprint through increased air pollution. Figure 52.1 Urban heat island. According to this figure, which parts of the landscape absorb heat and cool the atmosphere? The horizontal axis plots different regions and the vertical axis plots the values of temperature in Celsius. The data presented in the graph read as follows: Rural, 74 degree Celsius; Suburban, 82 degree Celsius; Commercial, 83 degree Celsius; Urban center, 95 degree Celsius (Heat energy radiates from urban areas); Parks, 78 degree Celsius (green walls, roofs, and parklands absorb heat and cool urban atmosphere); Residential, 81 degree Celsius; Agriculture, 72 degree Celsius. Urbanization also affects precipitation. Because of higher temperatures in the urban area, there is about 5 percent less snowfall than in the surrounding countryside. However, rainfall can be 5 to 10 percent higher in cities. The increased rainfall results from higher temperatures and from an abundance of dust particles, around which moisture collects. That is why fog and clouds are usually more frequent around cities. Urban Water Usage and Runoff Patterns An important part of a city’s ecological footprint is its impact on the water supply. The residential areas of cities are usually the greatest consumers of water. Water consumption can vary, but generally each person in the United States uses from 80 to 100 gallons (303 to 379 liters) per day in a residence. Residential demand is greater in drier climates and in middle- and high-income neighborhoods. Higher-income groups usually have a larger number of water-using appliances, such as washing machines, dishwashers, and sometimes swimming pools. Not only is the city a great consumer of water, it also alters water runoff patterns in a way that increases the frequency and severity of urban flooding. Pavement replaces vegetation in large areas of the city, and water cannot soak into the earth. Instead, precipitation is converted immediately into runoff and channeled through gutters, sewers, and stream channels. Water accumulates because there is no open ground for the water to seep into, resulting in flooding. In the countryside, water runs across soil and vegetation into stream channels and then into rivers, but there are no such meandering paths for water in cities. Runoff in cities is therefore concentrated and immediate, leading to urban flooding. Urban Vegetation Until about a decade ago, it was commonly thought that cities are made up mostly of artificial materials, such as asphalt, concrete, glass, and steel. However, recent studies show that about two-thirds of a typical North American city is composed of trees and herbaceous plants (mostly weeds in vacant lots and cultivated grass in lawns). This urban vegetation is a critical component of the urban ecosystem. Why? Urban vegetation influences the quantity and quality of surface water and groundwater, reduces wind speeds and temperature extremes, affects the pattern of snow accumulation and melting, absorbs thousands of tons of air pollution, and offers habitats for mammals, birds, reptiles, and insects. Urban vegetation also reduces noise pollution by muffling much of the city’s noise, affects the distribution of natural and artificial light, and is an extremely important component of soil, which controls hillside stability. Vegetation is particularly important in cities where homes are built on steep slopes. In several cases, landslides during heavy rains have sent homes plunging downslope. The City’s Environmental Effects on Other Areas Urbanization can also have environmental effects beyond the city. Urban living often encourages rising levels of consumption as city dwellers gain access to better jobs and acquire more disposable income. The growing demand for things like organic foods can impact areas far from urban centers. For example, as the United Nations has reported, tropical forests in Tabasco, an area 400 miles (644 kilometers) from Mexico City, have been transformed into cattle-grazing areas in response to city dwellers’ demands for meat. As you learned in Module 44, industrialization goes hand in hand with urbanization, which means that cities often feel the environmental effects of industrialization. But urbanization itself also affects the environment. Supplying enough energy, food, and water to large concentrations of people puts many stresses on the natural environment. Scholars call the spatial extent of an urban area’s impact on the environment the urban footprint. For example, Las Vegas, one of the fastest-growing urban areas in the United States, is located in a desert (Figure 52.2). It is expensive to construct the dams and infrastructure necessary to move water into the city from the Colorado River, and the resulting environmental damage to the surrounding region has been very costly. The dams alter the flows of water through the Colorado Valley, harming fish and disrupting aquatic life cycles. In addition, the energy required to divert the water to the city leads to higher greenhouse gas emissions, which reflect and trap heat on Earth’s surface. In other words, Las Vegas has a large urban footprint. Figure 52.2 Desert suburb. This suburb of Las Vegas extends into the desert. Providing water to its residents is costly and causes environmental damage. Water and Sanitation Many cities in developing countries have acute problems with water supplies and sanitation. We know that aging infrastructure leads to severe problems in the United States, such as dangerous levels of lead in the water (see the example of Flint, Michigan, in Module 51). The issues are different in some developing countries where infrastructure is lacking and where water might be obtained only at a public tap whose water is contaminated. There, millions of urban dwellers have no access to fresh, clean water. The World Bank estimates that around 65 percent of urban residents in developing countries do have access to a clean water source, but only about 40 percent are connected to sewers. Also, up to 90 percent of sewers discharge their untreated waste into a river, a lake, or the sea. Sanitation is also an issue in many cities. The collection and removal of garbage and solid waste occur in only about one-third of the world’s cities. The rest is dumped into canals, rivers, or gullies—or sometimes simply left in place to rot. Long stretches of rivers, estuaries, and coastal zones are polluted with industrial and human waste. Groundwater is polluted through the leaching of chemicals from uncontrolled industrial dump sites. Air Quality The concentration of automobiles in the world’s cities is a major source of air pollution, especially where regulations on pollution and vehicle emissions are poorly enforced or nonexistent. Car exhaust spews tons of lead, greenhouse gases, and many other toxic chemicals into the air we breathe. In low-income neighborhoods, the use of charcoal, wood, and kerosene for fuel and cooking is another significant contributor to air pollution. Additionally, in many cities with poor sewage disposal, air quality is worsened by airborne dried fecal matter. Many studies conducted by the United Nations, the World Bank, and the World Health Organization (WHO) show that megacities have dangerous levels of at least one major pollutant. WHO studies show that lead-bearing air pollutants reduce children’s IQ by an average of 3.5 points per year until they are seven years old. Overall, studies show that poor air quality resulting from automobile and other pollution-emitting sources is a cause of premature deaths, reduced thinking skills in children, and lost productivity. Energy The increased use of energy for heating, cooling, cooking, and electricity increases urban air pollution, particularly because much of our energy is produced by nonrenewable and polluting fossil fuels, such as coal, petroleum, and natural gas. Renewable sources, such as solar, wind, and water, as well as nuclear energy, are increasingly used as substitutes for nonrenewable fossil fuels, but the world is still heavily dependent on fossil fuels. How does energy consumption differ by world region? In 2018, China surpassed the United States in terms of total energy consumed. That same year, total energy consumption in the United States increased 3.5 percent, reaching a record high, partially driven by weather conditions of a hot summer and cold winter. In contrast, in 2018 overall energy consumption decreased by 1 percent in the European Union. A milder winter and energy efficiency improvements, such as an 18 percent increase in offshore wind capacity in 2018, are partially responsible for Europe’s decreasing energy consumption (Figure 52.3). Overall, however, global energy consumption grew significantly in 2018, increasing by 2.3 percent, driven by high growth in the demand for electricity and gas. More and more often, we hear about natural disasters that strike urban areas, killing people and destroying infrastructure. These natural disasters include tornadoes, floods, hurricanes, landslides, and earthquakes. In general, cities are not necessarily more vulnerable to natural disaster, except for the cities that are located near large bodies of water and that lie in the direct path of hurricanes and tsunamis. Instead, disasters are more destructive in the densely populated urban areas because so many people live there. Scientists have recently noted an increase in the number of natural disasters that they attribute to global climate change (Figure 52.4). The combination of increasing urbanization and a growing number of natural disasters means that more and more people’s lives are being impacted. Often, poor people are the most affected because they tend to live in structures that are not well built and in sections of the city that are more vulnerable. In the developing world, shantytowns are frequently situated on steep hillsides or poorly drained areas that are vulnerable to landslides, flooding, and other natural disasters. Figure 52.4 Urban risks arising from climate change. If you live in a city in North America, which risk is greatest? The horizontal axis shows reasons for risks and the vertical axis measures percent of cities reporting climate change risks from 0 through 100 with increments of 10. A legend above correates the colors used in the graph with the following cities. Africa, 12 cities, East Asia, 11 cities, Europe, 30 cities, Latin America, 23 cities, North America, 27 cities, and South Asia or Oceania, 7 cities. Approximate values follow, in the format region, then percentage reporting climate change risk. For temperature increase or heatwaves: South Asia or Oceania, 6; North America, 22; Latin America, 15; Europe, 20; East Asia, 10; Africa, 7, totaling to 80 percent. For Frequent or intense rainfall: South Asia, 5; North America, 15; Latin America, 15; Europe, 20; East Asia, 10; Africa, 9, totaling to 74 percent. For Drought: South Asia, 3; North America, 14; Latin America, 5; Europe, 15; East Asia, 5; Africa, 3, totaling to 45 percent. For Storms or floods: South Asia, 3; North America, 13; Latin America, 6; Europe, 8; East Asia, 3; Africa, 6, totaling to 39 percent. For Sea level rise: South Asia, 5; North America, 7; Latin America, 5; Europe, 12; East Asia, 2; Africa, 4, totaling to 35 percent. The International Federation of Red Cross and Red Crescent Societies have coined the term urban risk divide to reflect the idea that disasters and disaster risk become urban phenomena as the world’s population becomes increasingly concentrated in large cities. Some cities are better prepared for disasters than others. Compare, for instance, the human toll exacted by two major earthquakes in 2010. In Chile, the death toll from an 8.8-magnitude quake was in the hundreds, while in the island nation of Haiti, the death toll from a quake of slightly less magnitude was over 200,000. The wealthy, however, are not immune to natural disasters. Hurricane Sandy, which hit the coastline of New Jersey and New York in October 2012, disproportionately affected somewhat wealthier individuals. The storm caused $62 billion in damages and loss, with 375,000 homes destroyed, subway tunnels flooded, and business activities curtailed. How have urban residents and governing bodies responded to all of these negative environmental impacts? The answer depends on where you look. Some cities have been leaders in creatively confronting environmental challenges and reducing risk, while others have lagged behind. You might be surprised by which areas of the world rank the highest in disaster readiness (Figure 52.5). Latin American cities lead the pack, with 95 percent of the region’s cities engaging in some form of climate change adaptation planning, while U.S. cities lag behind all others at 59 percent. Why is the United States so far behind? The conversation about global climate change is a relatively recent one, coming at a time when many U.S. cities are facing severe budgetary shortfalls and even declaring bankruptcy. In addition, there are political barriers to addressing climate change, partly because some of the necessary changes are likely to cause unemployment. Figure 52.5 Climate change adaptation planning. Which region ranks highest in planning for climate change? Which region ranks lowest? The horizontal axis plots percentages ranging from 50 through 100 in increments of 10. The vertical axis has the names of countries or regions. Approximate data in the graph are as follows. United States, 58 percent. Asia, 67. World average, 68. Africa, 80. World average without U S, 85. Europe, 85. Australia and New Zealand, 87. Canada, 94. Latin America, 95. Cities can take some measures to lessen the impact of climate change on natural systems, humans, and the urban built environment. For instance, cities can reduce emissions of greenhouse gases by restricting the amount of pollutants emitted by urban industries, shifting to low-carbon and renewable fuels, and planting trees to reduce carbon dioxide. In addition, cities can encourage sustainable architecture. For instance, so-called “green roofs” and “green walls” provide surfaces that do not retain heat (thereby reducing the urban heat island) and absorb water (addressing rapid runoff) and carbon dioxide. In addition, these surfaces reduce urban noise levels and provide a pleasant environment for humans, as well as refuge for urban wildlife (Figure 52.6). Figure 52.6 Green walls. The city of Sydney, Australia, has developed a “green roofs and walls” initiative in an attempt to encourage more beautiful and environmentally urban surroundings. In many ways, the conversation about climate change is shifting from attempting to preserve earlier conditions to preparing for a very different-looking future. This conversation involves an acceptance of climate change as the new normal and seeks to respond to environmental threats by minimizing risk to human lives, livelihoods, and property. The Subject to Debate explores the environmental sustainability of urbanization. As you learned in Module 50, cities can grow and develop sustainably by implementing smart growth policies and New Urbanism city designs. But as we also saw, fragmentation of local governments can complicate coordinated responses to negative environmental impacts. Even so, with a little coordination, governments can take steps to fix problem areas within cities, curtail unsustainable growth, and lessen environmental damage to places outside the city. Within cities, properties whose use or development may be complicated by the potential presence of hazardous substances or pollutants are known as brownfields. There are hundreds of thousands of brownfields in the United States, including some prime downtown and waterfront properties. It is in the city’s best interests to remove or seal off any contaminants so that a site may be used again without any health concerns, a process known as brownfield remediation. The process for brownfield remediation depends largely on the zone and intended use of the property. For example, a parking lot requires a different level of cleanup than a lot being converted into a community garden. The city of Pittsburgh provides an example of brownfield remediation and redevelopment. Pittsburgh has a long history as a manufacturing center and is strongly associated with the steel industry. The decline of both of these industries left numerous brownfields in the city—sites of closed factories polluted by hazardous materials. In 1988, the Graduate School of Public and International Affairs at the University of Pittsburgh suggested that identification and redevelopment of brownfields within and around the city of Pittsburgh would benefit the region economically. SUBJECT TO DEBATE Can Urbanization Be Environmentally Sustainable? Preparing for the AP® Exam The fact that more than half of the world’s population now lives in cities has refueled the debate over the environmental impacts of increasing urbanization. On the one hand, increasing urbanization can be considered efficient. Cities concentrate human populations at one point in space, which leaves surrounding lands available for conservation, agriculture, and other low-density uses. Cities allow services to be delivered at a lower cost per person because more people can benefit from the urban infrastructure. On the other hand, these same concentrations of population lead to greater demands on resources that must be brought in from outside of the city, such as water, energy, and food. Are cities, then, sustainable? On one side of the debate are those who focus on the negative environmental impacts of large concentrations of people. Cities have a direct impact on the land, in terms of the amount of space they occupy and the pollution they create, but they also have indirect impacts because urban dwellers typically have higher incomes and consume more goods than do rural dwellers, which places additional stress on the environment. For example, more consumer demand for items such as meat, wood, and metal from city dwellers in, say, Vancouver can have adverse environmental impacts throughout Canada and parts of the Pacific Rim. Those who are optimistic about creating a more sustainable future with increasing urbanization argue that higher-density human settlements are better for the environment in the long run than less dense settlements. Even with the current growth rate of cities in terms of size and number, the extra space that urban cities take up does not, in itself, appear to be a major environmental stressor. Urban density actually helps maintain fragile ecosystems by keeping them free from human interference. Thus, they argue, policies geared toward dispersing the world’s population away from big cities are misguided. The real problem, they say, rests with unsustainable forms of production and consumption—the key issues on which the world’s attention should be focused. AP® Exam Tip To distinguish yourself among test takers, prepare some answers to explain the environmental impacts of urbanization besides simply stating “pollution”. Your success is in the details that exemplify real understanding. Continuing the Debate Consider the following questions about the environmental sustainability of urbanization: Can an increasingly urban world be sustainable? If so, how? If you live in a city, does your city have a sustainability plan? If so, how might you learn more about it? How vulnerable is your city to environmental or human-made threats? Has your city begun to plan for the effects of urbanization? Aerial view of New York City. Because of the high density of its population and its mass transportation system, New York City is considered to be a relatively “green” city. Urban parks, like Central Park, shown here, often provide important sanctuaries for flora and fauna in the heart of the city. In response, developers and government officials from surrounding regions cleaned up steel plants and other contaminated sites along the Monongahela River, converting them into impressive commercial, residential, and mixed-use projects. To remediate these brownfields, developers removed polluting pipes, tanks, and other objects; excavated and disposed of contaminated soil; and contained and surface-sealed large areas such as parking lots. In some cases, developers also used phytoremediation. Phytoremediation is the process of introducing plant species that produce chemicals that react with or degrade contaminants or draw up contaminants from the soil into shoots and leaves (Figure 52.7). Figure 52.7 Sunflowers growing in brownfield site. Sunflowers can be used for phytoremediation. There are many advantages of brownfield remediation and redevelopment: removal or treatment of harmful substances, increased property values, community pride and vitality, avoidance of urban sprawl, and economic benefits from reinvestment in blighted properties. In Module 51, we saw the importance of preserving open spaces and farmland. As cities sprawl, more and more land that used to be farmland is developed into nonagricultural uses, including large residential communities and infrastructure projects such as reservoirs and power plants. Studies conducted in the early 1980s found that many of the projects converting farmland to nonagricultural uses were funded by the federal government. In response, Congress passed the Farmland Protection Policy Act (FPPA), which grants municipalities oversight over federally funded development projects on farmland to minimize the effect of federal programs on the unnecessary and irreversible conversion of farmland to nonagricultural uses. Any project (federally funded or not) that would convert farmland to nonagricultural uses must undergo a land evaluation and site assessment and comply with the findings of the USDA/NRCS review. If the project’s impact on the environment is deemed too great, the developer is advised to consider alternative sites. You can easily imagine that replacing a farm with a large housing development ruins the agricultural potential of that area. But farmland can also be rendered unusable directly when farmers sell off individual parcels of their land or when the needs of nearby residential areas conflict with farms’ needs. Subdivisions or developments that do not border on existing settlements and that remove agricultural land from production are called scattered developments. Scattered developments can break up a farm so that it can no longer raise crops that require large plots of land. In addition, scattered development may force nearby farmers out of production through non-farm residents’ complaints about dust, odors, sprays, and noise. Also, new housing can cause a general rise in land values, leading to high property taxes, which farmers may not be able to afford. Finally, the shrinking of an agriculture-based economy in an area can encourage more and more farmers to close their farms and sell their land, accelerating the collapse of this part of the economy. In addition to FPPA, many communities have taken steps to protect agricultural lands. Strategies employed by local governments include agricultural zoning, agricultural buffers that limit how far city and suburban development can spread, and right-to-farm ordinances that protect farmers from nuisance complaints such as a rooster crowing at dawn or slow-moving farm equipment on rural roads (Figure 52.8).Urbanization does not necessarily mean environmental damage on a large scale. In fact, the higher densities of population in cities can actually be considered a form of sustainable growth: half the population of the world—the urban half—lives on just 3 percent of Earth’s landmass. This means that other areas can be protected and left relatively free from human use. Many countries in the developing and developed worlds are working on local and regional planning projects that, on the one hand, maintain urban boundaries and prevent sprawl and, on the other hand, protect natural environments outside urban areas from environmental degradation. These environmental conservation projects will become increasingly important in the coming years. With this Module, we conclude our adventures in urban geography. As we progressed through the Unit, we advanced from the origin and growth of cities to world cities, globalization, internal city models, and the challenges of urban dwelling and sustainability. Throughout the Unit, we looked at how geographers use both quantitative and qualitative data to study urban areas. All of this information will be helpful to you as the world’s urban population continues to increase. Whether you choose to live in a city or not, you can play a role in making cities more sustainable by supporting programs intended to decrease negative environmental impacts. The ecological footprint of cities is enormous and includes higher temperatures and higher levels of atmospheric pollution due to the phenomenon of the urban heat island. Cities use a great deal of water and are subject to flooding because they have little open ground for precipitation to seep into. Urban environmental vulnerability includes water and sanitation concerns, air quality, and high energy usage. Natural disasters are major challenges for cities of all sizes, particularly those in coastal locations. Responses to climate change are uneven across the world, with some cities actively working to reduce risk and others poorly prepared. 52-2 How can cities respond to the challenges of sustainability? Environmental conservation projects on a regional scale can help to protect natural environments outside urban areas from environmental degradation. Brownfield remediation and redevelopment have many advantages, including the removal and treatment of harmful substances, increased property values, and community pride and vitality. Farmland protection and preservation policies are intended to minimize the unnecessary and irreversible conversion of farmland to nonagricultural uses. Local communities have taken additional steps to preserve farmland by passing right-to-farm ordinances and preserving farmland as open space. Urbanization can lead to the efficient use of land, with a large portion of the population living in a relatively small area. Key Terms to Remember affordability agricultural surplus anti-displacement tenant activists automobile cities below market rate housing blockbusting boomburb (boomburg) brownfield remediation brownfields built environment capitalism central place central place theory city communism compact design concentric zone model de facto segregation decentralize diverse housing options ecological footprint edge city environmental injustice environmental justice environmental racism exclusionary zoning exurb Farmland Protection Policy Act (FPPA) first urban revolution fiscal imbalance fiscal squeeze fiscal zoning galactic city model or peripheral model gated community gentrification gravity model greenbelt Griffin-Ford model housing choice voucher program Hoyt model or sector model inclusionary zoning (IZ) infill development land tenure metropolis metropolitan statistical area micropolitan statistical area mortgage multiple-nuclei model New Urbanism NIMBYs perceived density phytoremediation primate city range rank-size rule redevelopment redlining scattered developments second urban revolution site situation slow-growth city smart growth social controls socioeconomic stratification sprawl squatter settlement streetcar suburb suburb suburbanization threshold urban urban area urban cluster urban footprint urban hearth areas urban heat island urban hierarchy urban renewal urban risk divide urban system urbanization urbanization rate urbanized area violent crime white flight world city zoning zoning regulations

Urbanization is the increasing movement of people from rural areas to cities, leading to changes in social structures, the economy, and the environment. The world has seen a rise in megacities, defined as cities with over 10 million inhabitants, which contribute significantly to globalization. Urban areas struggle with socioeconomic disparities, housing challenges, and environmental issues, including pollution and climate change. Inclusionary zoning policies aim to provide affordable housing, while gentrification can lead to the displacement of lower-income residents. Cities face the challenge of maintaining infrastructure and sustainability while addressing the needs of diverse populations. Different models, such as the concentric zone model and the sector model, explain urban structure, but many cities now evolve in ways that do not fit neatly into these theories. Responses to urban challenges include smart growth initiatives, new urbanism, brownfield remediation, and community engagement to ensure equitable access to resources and services. Ultimately, the success of urban areas depends on their ability to adapt and promote sustainability through innovative policies and community-driven solutions.

Urbanization refers to the increasing movement of people from rural areas to cities, resulting in significant changes in social structure, economy, and environment. The rise of megacities—urban areas with over 10 million inhabitants—plays a crucial role in globalization. Urban areas face challenges such as socioeconomic disparities, housing shortages, pollution, and climate change. Policies like inclusionary zoning aim to create affordable housing, while gentrification often displaces lower-income residents. Various urban models, such as the concentric zone and sector models, help explain city structure, though many cities now evolve in complex ways that defy these theories. Responses to urban challenges include smart growth initiatives, new urbanism practices, brownfield remediation, and community engagement to ensure equitable access to resources. The success of urban areas hinges on their ability to adapt and implement innovative, sustainable policies.