Size and DIstribution of Cities (College Board AP® Human Geography)

City Hierarchies

• Human geography has several methods for explaining the distribution and size of cities around the world. These include:

  • rank-size rule

  • primate cities

  • gravity model

  • Christaller’s Central Place Theory

Rank-size rule

• Rank-size rule describes statistical regularities in city distribution in countries and regions

  • Under the rank-size rule, the nth largest city will be 1/nth the size of the largest city

  • So, the second largest city will be ½ the size of the largest city in the country or region

Primate city

• A primate city is disproportionately larger than the next largest city in the country

  • London is an example of a primate city

  • It has a population of approximately 9.5 million

  • The second largest city in the UK is Birmingham with a population of approximately 2.7 million

Gravity model

• The gravity model explains the likelihood of interaction between two places based on

  • size

  • population

  • distance

Christaller’s Central Place Theory

• Christaller’s Central Place Theory explains the distribution of goods and services across an area

Hierarchies

• City hierarchies explain the ranking of cities based on their:

  • size

  • function

  • influence 

• Cities at different levels of the hierarchy have different political, economic, social, and cultural roles

The urban hierarchy

• World cities (or global cities) are at the top of the urban hierarchy

  • These cities serve as international hubs of economics, culture, and politics

  • Examples of world cities are:

    • New York

    • London

    • Tokyo

    • Paris

• Regional cities are in the middle of the urban hierarchy

  • They serve as hubs of regional or national trade, transportation, and administration 

  • Examples of regional cities are:

    • Washington, DC

    • Frankfurt

    • Istanbul

• Cities without extended economic or cultural significance are at the bottom of the urban hierarchy

  • They provide goods and services to local populations, but their influence does not extend past their immediate area

• Cities higher up on the urban hierarchy influence the cities below them

• Cities lower on the hierarchy usually depend on higher-tiered cities for resources and markets

• Cities at the top of the hierarchy usually attract the most resources, investment, and migration

Interdependence of Cities

• Cities are interconnected through networks of economic, political, and social relationships

  • Goods, services, information, and people flow between cities, increasing their interaction and contributing to globalization

• Economically, cities often take advantage of their comparative advantage and specialize in a particular industry or industries

  • They then rely on other cities for goods and services that they do not produce

  • For example, London specializes in finance while San Francisco specializes in technology

• Cities are linked together through global trade networks, with large cities serving as trade and finance hubs

• Smaller and larger cities within a country or region are connected through migration and commuting patterns

  • Migration from smaller to larger cities for jobs and education creates regional interdependence

• Large cities influence trends in art, music, fashion, and culture through migration, media, and tourism

• The gravity model predicts the interaction of places based on their population, sizes, and the distances between them

  • The gravity model theorizes that cities that are larger with larger populations will have a greater pull on nearby cities

  • People and goods will flow to the larger city

  • Cities that are closer together will have more interaction with one another than cities that are further away from each other

Distribution & Size of Cities

• There is a relationship between a city’s population size and its place on the urban hierarchy

  • A city’s ranking in the urban hierarchy can be predicted by the rank-size rule 

• The rank-size rule proposes that a country or region’s nth-largest city is 1/nth the population of the largest city

  • the biggest city is twice the size of the next biggest city

  • the third largest city is ⅓ the size of the largest city

  • the fourth largest city is ¼ the size of the largest city

• U.S. cities tend to follow the rank-size rule

• Benefits of rank-size rule cities include that multiple cities in the region or country share power and a variety of different goods and services are offered as a result

• Potential weaknesses of countries or regions that follow the rank-size rule are that communication and standardization are more difficult

Primate Cities

• A primate city is the main city in a country in terms of size and influence by a wide margin

  • Primate cities are disproportionately larger than the second and third-largest cities in the country or region

  • Because they are so much larger than other cities in their area, primate cities dominate the country or region’s economic, cultural, and political affairs

  • For example, cities like Paris (8x larger than the next city) and Buenos Aires (10x larger than the next city) are examples of primate cities

• The existence of primate cities can be beneficial because they attract:

  • international trade

  • business

  • tourism

• Primate cities can also be a negative influence because the vast majority of economic activity and services are concentrated in one place and the remainder of the country or region may be underserved

• Note that not all large cities are primate cities

  • Some of the world’s largest cities, such as Mumbai and New York City, are not primate cities because they are not more than twice as large as the next city in their respective countries

Christaller’s Central Place Theory

• In the 1930s, German geographer Walter Christaller developed the Christaller Central Place Theory to study patterns of urban land use

  • The Central Place Theory explains the distribution of goods and services across a region

• Renditions of Central Place Theory are easily identifiable based on the use of multiple, overlapping hexagons

Image: Cristaller's Central Place Theory

• In this theory, central places are urban centers that provide services to people living in the surrounding areas

• Central Place Theory relies on the concepts of threshold and range

Threshold

• A threshold refers to the number of people required to support a business and make it profitable

  • Examples of businesses with low thresholds include a donut shop, a gas station, or a corner store

  • Examples of businesses with high thresholds include a regional hospital, an airport, or a large department store

Range

• Range refers to the distance people are willing to travel for a particular good or service

  • Examples of low-range services are a coffee shop, a local pharmacy, or a chain restaurant

  • Examples of high-range services are a speciality hospital, a special store (such as one selling wedding dresses), or a concert venue