The Future of Urban Growth: Rates, Speed and Size(9)

Over the last 30 years, two patterns have gripped public and media attention: the speed of urban growth in less developed regions and the growth of mega-cities (those with 10 million or more people). Focusing on these two aspects can be misleading today.

In the first place, the real story is no longer the rapid rates of city growth but the absolute size of the increments, especially in Asia and Africa. The fact is, the overall rate of urban growth has consistently declined in most world regions (Figure 1).

In the second place, the mega-cities are still dominant, but they have not grown to the sizes once projected. Today’s mega-cities account for 4 per cent of the world’s population and 9 per cent of all urban inhabitants. This is an important slice of the urban world, but it will probably not expand quickly in the foreseeable future, as shown in Figure 2. Many of the world’s largest cities—Buenos Aires, Calcutta, Mexico City, São Paulo and Seoul—actually have more people moving out than in, and few are close to the size that doomsayers predicted for them in the 1970s.(10)

Some large cities are still growing at a rapid rate, but this is not necessarily bad. In a globalized economy, and in regions such as East Asia, rapid growth may be a sign of success rather than a cause for apprehension.(11) To be sure, some of the mega-cities associated with poverty grew very fast over the last 30 years. But these are increasingly seen as exceptions.

Among today’s 20 mega-cities, only six grew at rates consistently above 3 per cent a year over the last 30 years. The others experienced mainly moderate or low growth. Over the next 10 years, only Dhaka and Lagos are expected to grow at rates exceeding 3 per cent a year. Six will grow at rates under 1 per cent.(12)