Topic 6.2 Notes – Cities Across the World

What Urbanization and Suburbanization Are

Urbanization means an increasing percentage of a country’s population lives in urban areas. Urban growth means the number of urban residents gets bigger. A country can have urban growth without much urbanization if it was already highly urban.

Suburbanization is the outward movement of people and development from the central city into surrounding areas. That includes:

• homes
• jobs
• shopping
• schools
• hospitals
• other services

The central city and CBD used to be the main focus of jobs and services in a metro area. As metropolitan areas grow, that dominance often weakens.

Here’s the process chain APHG wants you to see:

1. Urbanization enlarges cities.
2. Suburbanization pushes growth outward.
3. Decentralization shifts jobs and services away from downtown.
4. Sprawl and new land-use patterns appear.

That last step matters a lot on tests. You usually need to connect the process to the map pattern or landscape, not just define the word.

Very Large Cities Around the World

These very large urban centers are not spread evenly across the world. The biggest clusters appear in Asia, with additional concentrations in Latin America, Africa, Europe, and North America.

Global distribution of major urban agglomerations

Megacity

A megacity has more than 10 million people in its urban agglomeration. That usually means the built-up urban area or metro area, not just the city proper, because legal boundaries vary a lot.

• Standard examples: Mumbai, São Paulo, Tokyo
• A city’s ranking can change depending on whether a source uses city proper, built-up area, or metro area

Metacity

A metacity has more than 20 million people.

• Every metacity is also a megacity
• Most megacities are not metacities
• Standard examples: Delhi and Tokyo

Where they are concentrated and why

On the map, the densest clusters are in East, South, and Southeast Asia. Today, the fastest growth of giant cities is concentrated in the semiperiphery and periphery, especially Asia, plus parts of Latin America and Africa. Earlier major-city growth centered more in Europe, North America, and Japan.

Why they grow:

• Rural-to-urban migration brings people seeking jobs, schools, health care, and safety
• Natural increase adds population when births exceed deaths
• Demographic momentum keeps growth going because many residents are young
• Economic restructuring concentrates manufacturing and services in major metros
• Transportation and communication links connect cities to markets
• Government investment and political centralization pull institutions and jobs into major cities

Why they matter

Huge cities create agglomeration benefits such as large labor pools, specialized services, and major transportation hubs. They can also face infrastructure deficits when housing, sanitation, water, and transit do not keep up, leading to congestion, overcrowding, pollution, and unequal access.

Outward Metropolitan Growth

As giant cities expand, growth often shifts outward inside the metro area.

Decentralization

Decentralization is the redistribution of people, jobs, commerce, and services away from the traditional CBD into multiple nodes. This creates a polycentric metro area.

• commuting becomes suburb-to-suburb, not only suburb-to-downtown
• driven by highways, cars, logistics networks, and telecommunications

Urban sprawl

Urban sprawl is low-density, dispersed, automobile-dependent outward growth onto rural land.

The image below shows a classic sprawl pattern with curving streets, cul-de-sacs, and separated subdivisions spreading across the metropolitan fringe.

Low-density suburban sprawl

Not all suburbanization is sprawl. A compact rail-based suburb is suburban, but it is not sprawling.

Key traits:

• separated land uses
• leapfrog development
• cul-de-sacs
• large lots
• shopping strips
• parking lots

Causes and effects:

Edge Cities, Exurbs, and Boomburbs

These are all products of suburbanization and decentralization, but each has a different pattern.

Edge cities

Edge cities are major suburban concentrations of offices, retail, services, and entertainment, often at highway intersections. They act like secondary business districts.

• standard example: Tysons, Virginia
• clue: job and shopping node outside downtown

Exurbs

Exurbs are low-density residential communities beyond the continuously built-up suburbs, but still tied to the metro area by commuting.

• semi-rural landscape
• large lots and scattered subdivisions
• clue: outer commuter zone

Boomburbs

Boomburbs are large, fast-growing suburban municipalities with big populations but suburban form and no dominant historic downtown.

• standard example: Mesa, Arizona
• clue: an entire suburban city grew rapidly

Comparing Cities Across Space and Time

In core countries, suburbanization often took off after mass car ownership and slower central-city growth. In the semiperiphery and periphery, urbanization and suburbanization often happen at the same time that total metro populations are still growing fast.

Categories can also change over time:

• an exurb can become a suburb
• a highway interchange can become an edge city
• a suburb can become a boomburb

The biggest global pattern to lock in is this: the fastest current growth of megacities and metacities is outside the traditional core.