Recognise and explain the spatial distribution of megacities and world cities and the shift toward the developing world

What this dot point is asking

QCAA wants you to recognise and explain where the world's megacities and world cities are, and why that distribution has changed over time. This is the spatial-pattern dot point for Topic 2: before you study one megacity in depth you need the global picture. The skill is describing the distribution with geographic language (clustered, shifting, concentrated in Asia) and explaining the shift from the developed to the developing world. Strong answers distinguish a megacity (a size category) from a world city (a power and connectivity category), use real city examples, and explain the pattern with reference to migration, economic development and globalisation.

The answer

Defining megacities and world cities

A megacity is a size category: an urban agglomeration usually defined as having more than 10 million inhabitants. The count of megacities has grown rapidly, from a handful in 1970 to more than thirty today, and is projected to keep rising. A world city (or global city) is defined differently, by influence and connectivity rather than population. World cities are command centres of the global economy, hosting financial markets, corporate headquarters, advanced services and international institutions. London, New York, Tokyo and Singapore are top-tier world cities. A city can be both, one, or neither: Lagos is a megacity rising in global influence, while Singapore is a powerful world city below the megacity size threshold.

The shifting distribution

The distribution of megacities has shifted dramatically. In the mid-twentieth century the largest cities were in the developed world (New York, London, Tokyo). Today the largest and fastest-growing megacities are overwhelmingly in the developing world, concentrated in Asia and increasingly in Africa. Tokyo, Delhi, Shanghai, Dhaka, Sao Paulo, Mexico City, Cairo and Lagos lead the list, and Africa's cities are now growing fastest. This shift reflects where rapid rural-to-urban migration and high natural increase are occurring.

Why the distribution has shifted

Several processes explain the move toward the developing world:

• Rural-to-urban migration. People move to cities seeking work, services and opportunity (pull factors) and pushed by rural poverty, mechanisation and land pressure (push factors).
• Natural increase. Youthful urban populations in the developing world add growth through births, not just migration.
• Economic development and industrialisation. Manufacturing and services concentrate in cities, drawing labour.
• Globalisation. Investment, trade and communications concentrate economic activity in connected cities, reinforcing the largest.

In the developed world, by contrast, urbanisation is already near complete and populations are ageing and stable, so few new megacities emerge there.

World city networks and primacy

World cities are best understood as a network rather than a list. They connect through flows of capital, information, people and goods, and their rank depends on how connected and influential they are. Some national urban systems show urban primacy, where one city is far larger and more dominant than any other, such as Bangkok in Thailand or Lima in Peru. Primacy concentrates economic and political power and can leave the rest of the country underserved.

Reading the pattern

Describe the global distribution with geographic language: megacities are clustered in Asia, increasingly present in Africa, fewer and slower-growing in the developed world. Note the direction of change over time (the shift south and east) and the association with development, migration and globalisation. This framing matters because it sets up the deeper case study of a single megacity in the developing world.

Examples in context

Example 1. Tokyo. The world's largest urban agglomeration and a top-tier world city, showing that the developed world still hosts a leading megacity even as growth concentrates elsewhere.

Example 2. Lagos. A rapidly growing African megacity driven by rural-to-urban migration and high natural increase, illustrating the shift of urban growth toward Africa.

Example 3. Singapore. A powerful world city below the megacity size threshold, showing that global influence and connectivity, not population, define world city status.