Population Distribution, Population Density, and Physical and Human Factors of Settlement

Global Human Population Distribution and Density

  • Humans live on only a small part of Earth's total land surface.

  • Over the last two centuries, world population grew very fast:

    • There are now 7×7 \times as many people as there were in the year 18001800

    • In the year 18001800, the global population was about 1 billion1 \text{ billion} people.

    

  • Even though overall population density has gone up, where people live (population distribution) has stayed mostly the same:

    • Most growth happened in regions that were already settled.

    • Example: Eastern China was heavily populated in 18001800 and remains one of the most crowded areas today.

    

  • Because the amount of good land stays the same, people adapted by living closer together (higher density) on that same good land.

Key Concepts in Population Geography

  • Human geography studies where people live and why they live there.

  • Two main ideas govern this study:

    • Population Distribution: The pattern of where people live across Earth. Maps show which areas are crowded, spread out, or empty.

    • Population Density: A quantitative measure of the average number of people per unit of land area, expressed per square mile or square kilometer (people/mi2\text{people/mi}^2 or people/km2\text{people/km}^2). It measures how crowded a place is.

    

  • Practical uses for density and distribution data:

    • Drawing boundaries for voting districts.

    • Planning where to build new housing developments.

    • Helping governments plan roads, schools, and public services.

    

Types of Population Density

  • Demographers (people who study human populations) use three specific measures of density:

    • Arithmetic Population Density:

    • The total number of people divided by the total land area.

    • Formula: Arithmetic Density=Total PopulationTotal Area\text{Arithmetic Density} = \frac{\text{Total Population}}{\text{Total Area}}

    • Example: In 20192019, the United States had about 328,239,523328,239,523 people and 3,841,999 sq mi3,841,999 \text{ sq mi}, resulting in an arithmetic density of 85.4 people/sq mi85.4 \text{ people/sq mi}.

    • Limit: It only gives a simple average and does not show where people actually live inside that country or area.

    • Physiological Population Density:

    • The total number of people divided by the amount of arable land (land suitable for growing crops).

    • Formula: Physiological Density=Total PopulationArable Land Area\text{Physiological Density} = \frac{\text{Total Population}}{\text{Arable Land Area}}

    • High physiological density means a country has many people relying on a small amount of farm land.

    • Countries with very high physiological density (like Egypt or Japan) must import food or use advanced technology to feed their populations.

    • Relates to carrying capacity, which is the maximum number of people the land can support without damaging the environment.

    • Agricultural Population Density:

    • The number of farmers divided by the amount of arable land.

    • Formula: Agricultural Density=Total FarmersArable Land Area\text{Agricultural Density} = \frac{\text{Total Farmers}}{\text{Arable Land Area}}

    • Shows how efficient farming is in a region:

      • Developed countries (like the Netherlands) have a low agricultural density because farmers use modern machines and technology, requiring fewer workers.

      • Developing countries (like Bangladesh) have a high agricultural density because more people work as manual farmers without modern equipment.

        

    

Spatial Patterns of Population Distribution

  • Looking at smaller areas shows three main arrangement patterns of housing and communities:

    • Dispersed (Even) Pattern: People are spread out evenly across the land area. Common in suburbs, farming areas, and ranching regions.

    • Clustered (Nucleated) Pattern: People group tightly together in one spot. Common when people live near a central feature (like a church or water source) or for shared defense.

    • Linear Pattern: People settle in a straight line along transit corridors, such as rivers, roads, or railway lines.

    

Physical Factors Influencing Settlement

  • Basic Survival Drivers:

    • Early humans needed immediate access to food, fresh water, and shelter.

    • Modern humans still need these exact same basics, keeping global population patterns very similar over time.

    

  • Key Environmental Factors:

    • Midlatitudes: Most people live between 30∘30^\circ and 60∘60^\circ north and south of the equator due to moderate weather and fertile soil. Most midlatitude land is in the Northern Hemisphere.

    • Low-Lying Areas: People prefer flat, low-elevation areas because they have better soil for crops and are close to oceans for trade, food, and milder temperatures.

    • Fresh Water: Populations cluster heavily around rivers and lakes for drinking water, crop irrigation, trade, and fishing.

    

  • Environmental Barriers (Sparsely Populated Areas):

    • High mountain ranges (harsh terrain and cold climate).

    • Dry deserts (lack of fresh water).

    • High-latitude cold climates (short growing seasons).

    • Tropical zones (poor soil quality and higher disease rates).

    • Polar regions (continually frozen with no permanent populations).

    

Human Factors Influencing Settlement

  • Social and Economic Attractions:

    • People move toward existing human clusters for job opportunities, safety, and to be near family and friends.

    • This causes city (urban) populations and densities to grow continuously.

    

  • Transportation Networks:

    • People prefer living near trade routes. Roads, railways, and rivers create linear settlement patterns.

    

  • Political Decisions:

    • Government decisions can place communities in isolated places.

    • Example (Alert, Canada): In 19501950, Canada built a military base named Alert in the far north to monitor the Soviet Union. Despite severe cold, snow, and ice, Alert is the northernmost permanent settlement in the world.

    

Impact of Scale and Time on Population

  • Scale of Analysis:

    • Global Scale: High mountains (like the Himalayas, Andes, or Rockies) have low population density everywhere due to harsh climates.

    • Regional Scale: Climate explains population differences across a state (e.g., coastal California is densely populated, while interior deserts and mountains are sparsely populated).

    • Local/City Scale: Climate variation across a single city is tiny, but people prefer higher elevations for cooler breezes, flood protection, and nice views.

    

  • Changes Over Time:

    • Seasonal Changes: Population density shifts with seasons. For example, "snowbirds" move from cold northern states to warmer states like Florida or Arizona during winter.

    • Daily Changes: Population density changes based on time of day. For example, Manhattan in New York City has about 1.5 million1.5 \text{ million} permanent residents, but its population rises to about 3 million3 \text{ million} during weekdays as commuters arrive for work.