Why the cities have grown

Posted: 18 September 2002

Author: David Satterthwaite

The rapid growth of towns and cities, both in the North and the developing South, has been underpinned by large economic, social, political and demographic changes, says David Satterthwaite, in this specially commissioned article.

The most important of these changes is the large expansion in the world economy (which increased more than fivefold between 1950 and 1990) and the shifts in employment patterns from agricultural and pastoral activities (dispersed in rural areas) to industrial, service and information activities (highly concentrated in urban areas).

The nations with the most rapid increases in their levels of urbanization are generally those with the most rapid economic growth while the nations with the highest per capita incomes are generally those with the highest proportion of their population in urban areas. The increasingly international nature of world production and trade (including the very rapid expansion in the value of such trade) has influenced urban trends in most nations. Many cities have grown rapidly because of their roles within this global system.

Demographic changes have also shaped urban change. Most significant has been rapid population growth rates, although these have declined significantly in most nations. In many nations, urban change has also been much influenced by changes in the size and composition of households (for instance smaller average household sizes have often meant that demand for housing grew more rapidly than the growth in population) and in age structures.

Colonial influences

Political changes have also had profound influences on urban growth in the last 50 years. The dissolving of colonial empires helped to underpin rapid urban change in most of Africa and Asia between the 1950s and the 1980s. More recently, the collapse of the Soviet Union and its economic block and the breaking up or reshaping of many nations in Europe impacted on the movement of people.

One of the main reasons why many cities in Africa grew so rapidly during the 1960s and 1970s was that they began from such a small base. This was largely because the colonial powers had restricted the rights of their national populations to live and work in urban centres. Another reason was the achievement of political independence and the development in urban centres of new government and educational institutions.

Wars and civil conflicts in Europe and Africa have brought major shifts in populations; the number of international refugees has risen to unprecedented levels and a considerable proportion have come to live in cities. Changed political structures and economic policies in many countries have also brought urban changes - notably in China, with its very rapid economic growth since the late 1970s.

In much of Latin America, urban systems were reshaped during the 1980s and 1990s by the introduction of or return to democratic rule, the shift in economic policies towards export promotion and, in many nations, some decentralization of power.

Overall, while broad trends towards increasingly urbanized societies can be discerned in much of the world, the scale and nature of such trends and their underlying causes differ much from country to country as they reflect different political and economic structures. They also differ within each country regionally and over time.

Future cities

Despite the long-term trend towards more urban societies, the world in 2000 proved to be less urbanized and less dominated by large cities than most people had predicted. Although many documents claim that more than half the world now lives in cities, this is not borne out by the latest UN statistics.

More than half the world's population still lives in rural areas (the United Nations Population Division estimates that around 2007 the world's urban population will exceed its rural population for the first time) and a large section of the urban population live in small administrative centres and market towns which are too small to be considered as cities. In many such urban centres, much of the workforce depend on agriculture or on enterprises serving rural populations. Only a few per cent of the world's people live in mega-cities. CairoCairo's population is growing fast© Gary John Norman/Panos Pictures There are also large gaps in our knowledge about the scale of urban change in recent years. The scale and nature of urban trends during the 1990s will only become known when new data become available for censuses held in 2000 and 2001. For many African nations, there has been no census during the last 15 to 20 years and as yet, no alternative way of measuring the population size of nations, regions and cities has been devised.

In some nations, all settlements with more than a few hundred inhabitants are urban centres; for others, it is only those in settlements with 10,000 or 20,000 inhabitants.

Small settlements

Since a considerable proportion of the world's population live in settlements with between 500 and 20,000 inhabitants, a nation's level of urbanization is much influenced by whether settlements are classified as urban. This also means that the scale of the world's urban population is strongly influenced by the urban criteria used within a few heavily populated countries.

If the Indian or Chinese government changed the criteria used in their censuses to define urban centres, this could increase or decrease the proportion of the world's population that is 'urban' by several percentage points. Indeed, there are good reasons for thinking that the current criteria used in China considerably understate the size of its urban population.

Changes in the criteria used to define urban centres by the Nigerian census authorities could significantly alter figures for the level of urbanization in sub-Saharan Africa; similarly, just as changes in Brazil could significantly alter South America's level of urbanization. Thus, the level of the world's urban population is best understood not as a precise figure (47 percent in 2000) but as being between 40 and 55 per cent, depending on what criteria are used to define what is an urban centre.

An urban future?

Most commentators assume that the world will continue to urbanize far into the future - even if most admit that the speed and size of the change has been over-stated. In its most recent projections, which considerably reduce the scale of urban growth predicted up to 2025, the United Nations suggests that the world will have 58 per cent of its population living in urban areas by the year 2025. Africa is predicted to have 52 per cent of its population living in urban areas by then. But such projections should be viewed with caution.

Street Children, Maputo, Mozambique© Mark Schlossman/Panos Pictures

Given the links between economic and urban growth, a steady increase in the level of urbanization among less urbanized nations is only likely if they have steadily growing economies. While stronger and more buoyant economies for the world's lower-income nations should be a key goal for the world community, the current prospects for most such nations is not encouraging, within the current world economic system.

Many of the lowest income nations have serious problems with political instability or civil war and most have no obvious advantage on which to build an economy that prospers and thus urbanizes.

Resource shortages

There are also grounds for doubting whether a large proportion of the world's urban population will come to live in very large cities. Many of the world's largest cities have very slow population growth rates. For some, further expansion is hindered by resource shortages - water shortages, for example, will inhibit the development of many cities in semi-arid regions. Many large coastal cities are particularly at risk from the sea level rises and more frequent and severe extreme weather events that will come with global warming.

Meanwhile, in many nations, much new investment is going to specific medium size cities that are well located in relation to the largest cities and to transport and communications systems. These are helping to create urban systems that are less dominated by very large cities.

In regions with advanced transport and communications systems, rural inhabitants and enterprises can enjoy standards of infrastructure and services and access to information that historically have only been available in urban areas. Thus, both low and high-income nations may urbanize less than anticipated, although for very different reasons.

This article was written for Planet 21 by David Satterthwaite, Director of the Human Settlements Programme at the London-based International Institute for Environment and Development (IIED). He has also contributed to our Facts and Figures report on cities.