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How Cities Grow

How the Cities Grow

The world's urban population is growing fast. Within a few years - and certainly by 2005 - for the first time in human history, half the 6.5 billion people of our planet will be living in towns and cities.That is huge change. In 1950, only 29 per cent of the world's population of 2.5 billion were urban dwellers.  And 83 per cent of the developing world's people were still living on the land. If the UN projections are to be believed by 2025 over 60 per cent of the world's 8.3 billion global citizens will be living in towns and cities. While attention is often focused on the world's biggest mega cities such as Sao Paulo and Bombay, they contain only a relatively small proportion of all urban dwellers. Today, only about 15 per cent of urban dwellers live in cities with more than 5 million people, while over 60 per cent live in towns and cities of one million or fewer. Nor is the proportion likely to change dramatically. The UN projects that by 2025 18 per cent of the urban total will be in cities with over 5 million people.

In fact, the speed of growth in most mega cities slowed during the 1980s, so that some of the early projections have had to be drastically revised. In the early 1970s, for example, the UN projected that Mexico City would grow to over 31 million by the year 2000. The latest (1994) estimate now expects that figure to be 16.4 million. Others cities where estimates for end of century numbers have had to be scaled down include Rio de Janeiro (from 19.4 to 10.6 million), Calcutta (19.7 to 12.7), Cairo (16.4 to 10.7) and Seoul (18.7 to 12.3). Other projections have proved more accurate, as in the case of Bombay, which is still expected to house over 18 million people by the year 2000.

Overall the picture is a mixed one. Some of the 30,000 urban centres in the South grew very fast in the 1980s, some grew rapidly and many grew slowly or not at all. In general, the greatest growth took place where economic activity was most buoyant, as in China. According to David Satterthwaite, it is no accident that 199 of the world's 281 million-plus cities are found in the world's 25 largest economies. What is unprecedented, is the number of countries which are rapidly urbanizing and the number of cities that are growing rapidly. Many of today's million-plus cities have seen numbers grow tenfold in 40 years. These include places such as Amman, Curitiba, Dar es Salaam, Dhaka, Khartoum, Lagos, Nairobi and Seoul.

Also without precedent is the appearance of the huge agglomerations, never experienced before. In 1940, only New York and London had more than 5 million people. By 1990 there were 30 cities with over 5 million people of which 22 had over 8 million. Ten of these larger mega cities are in Asia, which is projected to add a further nine by 2025. Whether mega cities continue to grow, or to decentralize away from the dominant city into larger regional urban groupings, depends on many and varied factors, including the development of modern communication and transport systems.


Shockingly little is known, with certainty, about urban migration, though some estimates are that it may account for between 40 and 60 per cent of annual urban population growth. Migration is clearly more significant in rapidly industrializing regions such as Asia and parts of Africa. China, for example, may see 200 million more rural labourers looking for work in the cities over the next decade. In other regions that have largely completed the urban transition, such as Latin America, Europe and North America, it is less significant. Migration across borders to urban centres is a growing phenomena. For example, as transport links improve and economic barriers fall the migration north into Mexico and the United States is increasing. The recent civil war in El Salvador prompted nearly a fifth of the population to leave the country, mostly to the United States.

Though many migrants work in the informal sector, with low pay and little security, surveys suggest that the move to the city does improve their situation. One survey in New Delhi found that poor migrants from the countryside found their income was more than twice what they could earn in the village. Urbanization has also had a generally positive effect on the access to reproductive health care, the importance of which for the health of mothers and infants cannot be over stressed.  It has played a key role in assisting the decline in the average family size in developing countries from over six children in the 1950s to under four today.

Along with education, income and health care, the decline in birth rates correlates closely with urbanization. Despite all the environmental hazards, life expectancy is significantly longer and infant mortality significantly lower in urban areas, as against rural ones. Surveys in 17 countries showed that children under two had a 25 per cent better chance of survival by living in town rather than in the country. At the same time, the relative concentration of the poor in towns and cities is increasing. By the year 2000, UN estimates suggest that half the world's poorest people, or some 420 million, will be living in urban settlements .At the same time, the relative concentration of the poor in towns and cities is increasing.  By the year 2000, UN estimates suggest that half the world's poorest people, or some 420 million, will be living in urban settlements. This represents an institutional as well as a political challenge in dealing with rapid social, economic and demographic change.

This article has been prepared with the generous assistance of Robert Livernash, Senior Editor at the World Resources Institute (WRI) in Washington and David Satterthwaite, Director of the Human Settlements Programme at the International Institute for Environment and Development in London. It is partly drawn from World Resources 1996-97, published by WRI.


© Copyright: People & the Planet 1996

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