MOD 47
MODULE 47: The Size and Distribution of Cities
LEARNING GOALS
47-1 Describe an urban system.
47-2 Explain how the rank-size rule and primate city rule help to explain the urban hierarchy.
47-3 Describe central place theory.
47-4 Describe the gravity model.
Urban Systems
47-1: Definition of an Urban System
Urban System: A set of interdependent cities or urban places connected by networks.
Includes the examination of size and relationships among cities.
An urban system is often structured within geographical territories such as a nation, state, or province.
It encompasses towns and cities along with their hinterlands.
Facilitates the exchange of goods, services, ideas, money, and labor across the territory.
Example: Urban Systems in Washington State
Overview of Map (Figure 47.1): Illustrates the urban systems of the Pacific Northwest, specifically Washington and part of Oregon.
Major cities include:
Seattle, Tacoma (around Puget Sound).
Spokane Valley, Yakima, and Portland metropolitan area.
Infrastructure: Key freeways include:
Interstate 5: North-South route through Seattle and Portland.
Interstate 90: East-West route connecting Seattle to Spokane.
Interstate 82: Southeast route branching from Interstate 90.
Interstate 94: East-West connection through Portland.
Population distribution:
Cities with 500,000+: Seattle, Portland.
Cities with 100,000 - 499,999: Tacoma, Bellevue, Everett, Spokane.
Cities with 25,000 - 99,000: Bellingham, Marysville, Yakima, and many others.
Spatial Organization:
Western Washington: More urbanized with interconnected cities via major highways.
Eastern Washington: Characterized by agricultural land and smaller towns surrounding Spokane, lacking the suburban sprawl of the west.
Rules to Explain Urban Hierarchy
47-2: Concepts of Urban Hierarchy
Urban Hierarchy: A ranking of cities by size and power.
Two Rules for Urban Hierarchy:
Rank-Size Rule:
States that the population of a settlement is inversely proportional to its rank in the urban hierarchy.
Mathematical definition: The population of city #n can be described as:
ext{Population of city #n} = rac{ ext{Population of largest city}}{n}Example from the U.S.: If New York City has 8 million people:
City #2 (Los Angeles) would then have approximately 4 million (half).
City #3 (Chicago) would have approximately 2.67 million (one-third).
Statistical Findings:
The correlation between cities is often loose and more of a tendency than a strict rule (Table 47.1).
Table 47.1: Ranking of Settlements in the U.S.
| Rank | City | Population |
|------|----------------|-------------|
| 1 | New York City | 8,622,357 |
| 2 | Los Angeles | 4,085,014 |
| 3 | Chicago | 2,670,406 |
| 4 | Houston | 2,378,146 |
| 5 | Phoenix | 1,743,469 |
| 6 | Philadelphia | 1,590,402 |
| 7 | San Antonio | 1,579,504 |
| 8 | San Diego | 1,469,490 |
| 9 | Dallas | 1,400,337 |
| 10 | San Jose | 1,036,242 |The rank-size pattern is prevalent in developed countries but often less applicable in developing countries.
Primate City Rule:
Describes a scenario where the largest city has more than twice the population of the second-largest city.
This city typically dominates the economic, political, and cultural landscape.
Example: Lagos, Nigeria with over 15 million people, significantly larger than Kano (2nd largest) with 4.2 million and Abuja (3rd largest) with 4.0 million.
Implications of Urban Hierarchy Rules
Rank-size is a tendency seen primarily in nations with more even economic distributions, while the primate city is observable in nations where a single city significantly overshadows others.
Christaller’s Central Place Theory
47-3: Central Place Theory Overview
Central Place Theory: A model that explains the location of cities based on their role as providers of goods and services.
Developed by Walter Christaller in 1933, based on five critical assumptions:
The region's surface is flat with no physical barriers (mountains, rivers).
Soil quality is uniform across the region.
Population and purchasing power are evenly distributed.
Transportation networks allow direct travel between any settlements.
Goods and services can be supplied in all directions up to a certain distance.
Purpose: To categorize cities by their ability to provide services based on distance and demand for products.
Service Categories:
Low-Order Goods: Items that consumers buy frequently (e.g., bread, milk) that require short travel distances.
High-Order Goods: Special items or services (e.g., art museums, specialized medical services) that entice consumers to travel further for acquisition.
Hexagonal Service Areas: Service areas shaped in hexagons; larger cities provide services to wider areas than smaller ones.
Visualization of Central Place Theory (Figure 47.4)
Highlights how cities and towns serve as central places with different orders based on the size and distribution of hexagonal service areas.
Hierarchy of Central Places:
First-Order Places: Major cities (international marketplaces).
Second-Order Places: Important regional cities.
Third-Order Places: Smaller towns.
Fourth-Order Places: Hamlets providing local goods.
Modern Application and Relevance of Central Place Theory
While providing useful insights, Christaller’s theory shows limitations in today’s urban landscape:
Population and income are not evenly distributed, contradicting the second assumption.
Technological and geographical advancements have shifted the importance of traditional transportation routes, emphasizing communication networks instead.
Example of urban evolution: Oakland vs. San Francisco regarding port activities and economic roles.
Current Port Rankings (2023):
Port of Los Angeles.
Port of Long Beach.
Port of Oakland.
Ports of Tacoma and Seattle.
Conclusion
The study of urban systems, rules of urban hierarchy, and central place theory provides a comprehensive framework to analyze the distribution and characteristics of cities. Understanding these concepts is vital for geographers and urban planners as cities evolve and adapt to new realities.