Urbanization & City Systems

You’ll be able to

Explain urbanization, suburbanization, and the growth of world cities
Apply the rank-size rule, primate cities, and central place theory
Distinguish world/global cities, megacities, and metacities

Urbanization and its waves

Urbanization is the growing share of people living in cities and the expansion of urban areas, driven by rural-to-urban migration and natural increase. Developed regions urbanized during industrialization; today the fastest urbanization is in the developing world. Later stages bring suburbanization (growth of residential rings around the city), sprawl (low-density outward spread), edge cities (business nodes on the periphery), and even counter-urbanization (movement back to smaller towns). A world (global) city — New York, London, Tokyo — commands a disproportionate share of global finance and connections regardless of raw population.

City-size rules: rank-size vs. primate

Two patterns describe a country’s city sizes. The rank-size rule holds that the nth-largest city is 1/n the size of the largest — the 2nd city is half the largest, the 3rd a third, and so on (roughly the U.S.). A primate city is disproportionately larger than all others, dominating economy and culture — Paris dwarfs every other French city; Bangkok dominates Thailand. A primate-city pattern often signals a smaller or formerly colonial economy centered on one hub, while a rank-size hierarchy suggests a more balanced, developed urban system.

Central place theory

Walter Christaller’s central place theory explains the size and spacing of settlements as service centers. Two concepts drive it: the threshold (the minimum number of customers needed to support a service) and the range (the maximum distance people will travel for it). Low-threshold, short-range services (a convenience store) appear in many small towns; high-threshold, long-range services (a specialist hospital, an opera house) appear only in a few large cities that serve wide hinterlands. The result is a nested hierarchy of many small places and few large ones.

Worked example

A country’s largest city holds 8 million people; if it followed the rank-size rule, how large would the 2nd and 4th cities be? The actual 2nd city has only 600,000. What does the real pattern indicate?

1.Rank-size rule: the nth city ≈ 1/n of the largest. So the 2nd city ≈ 8,000,000 ÷ 2 = 4,000,000.
2.The 4th city ≈ 8,000,000 ÷ 4 = 2,000,000.
3.The actual 2nd city (600,000) is far below the predicted 4,000,000 — the largest city vastly outweighs the rest.
4.A single dominant city far larger than all others is a primate city, so this country has a primate-city distribution rather than a rank-size one.

Answer: Under the rank-size rule the 2nd city would be 4 million and the 4th city 2 million. Because the actual 2nd city (600,000) is a fraction of that, the largest city is disproportionately dominant — a primate city pattern, not a rank-size hierarchy.

Checkpoint

Paris is far larger than the second-largest city in France and dominates the nation’s economy and culture. This makes Paris a:

Tip

In central place theory, threshold = the minimum customers a service needs to survive; range = the maximum distance people will travel to reach it. High-order goods (specialist surgery, luxury retail) have large thresholds and ranges, so only big cities offer them; low-order goods sit in every small town.

Checkpoint

A specialized cancer hospital exists only in a few of a region’s largest cities, while convenience stores are found in nearly every town. Central place theory explains this because the hospital has a:

Answer the 2 checkpoints as you read.