The urban explosion - urban population

In 1950, there were 155 million more city-dwellers in the developed than in the developing countries; by 1970, there were only 30 million more. Since then, the developing countries have experienced an unprecedented wave of migration from the rural areas and, as a consequence, urban populations have multiplied by a factor of five or even six.

By the end of this century, nearly half the world population will be living in an urban environment. The number of city-dwellers in the developing world will total 1.9 billion, twice the total for the developed countries. At the same time, the rural population, which by then will be getting on for 3 billion, will continues its inexorable exodus towards the great conurbations.

In regions such as Europe, towns developed at a moderate pace as a logical consequence of the process of industrialization. This process increasingly enhanced the importance of socio-professional groups employed in industry and the service sector, the two main constituent groups of urban populations in the developed countries.

In the developing countries, however, migration flow to the cities began without this prior stage of industrialization and at a frenetic rate; as a result, urban growth in those countries is today three times as fast as in the industrialized countries. One of the most serious consequences of headlong urbanization has been to denude the rural areas of a large proportion of their active manpower and this has entailed a growing deficit in the production of foodstuffs. As a result, many countries of the South that were once self-sufficient in food have now become major importers of cereals even though they have at their disposal large areas of agricultural land.

The ideal city

Economists and social scientists have long been concerned with the question as to whether there is an optimal size for cities. For some experts, the optimal upper threshold, especially as far as employment is concerned, is around 500,000 inhabitants. At between 1 and 2 million inhabitants the critical point is reached beyond which maintenance of the general standard of living becomes more difficult. These, however, are only average estimates; it is clearly not possible to establish an ideal size that could be applied to all cities in all countries. It would be better to aim at achieving reasonable rates of urbanization with moderate growth and with limited megalopolitan development.

Nevertheless, urban growth, particularly in the developing countries, continues at a giddy pace. By the end of this century, the world will have five giant megalopolitan areas with populations of 15 million or more, three of which will be in the developing world.

According to United Nations estimates, the great cities in the industrialized world have almost all reached the point of maximum growth at which they are likely to remain for another thirty or so years. Things are shaping very differently, however, in the less developed regions, where many cities that did not figure among the great conurbations in the 1970s now take pride of place among the great megalopolitan areas of the world.

Mexico City, Sao Paulo, Calcutta and Bombay, for example, which during the 1970s stood sixth in the world ranking topped the 10 million mark in 1985 to join the ranks of the world leaders. In the year 2000, Mexico City will have 26 million inhabitants, Sao Paulo 24 million and Calcutta and Bombay a minimum of 16 million each. New urban agglomerations of 12 to 13 million inhabitants will also appear, including the Cairo/al-Jizah/Imbabah conurbation, Djakarta, Baghdad, Teheran, Karachi and Istanbul.

United Nations experts have carried their population projections up to the year 2025, at which time they estimate that there will be 93 cities with more than 5 million inhabitants, of which 80 will be in the developing world. There will be unimaginable growth, with the population of Abidjan being multiplied a hundredfold in 20 years, the population of Mexico increasing by 2,000 a day and the population of Cairo swelling by 40,000 a month.

Tentacular

urbanization

In the developing countries, urban population growth results primarily from migration and from the geographical and spatial spread of cities rather than from natural growth (excess of births over deaths). Nevertheless, the fertility of immigrant families and of inhabitants of areas absorbed by the spread of the towns often remains, for at least a generation, higher than that of those who have been city-dwellers from birth. When this period of adaptation is completed, the fall in the fertility rate is often offset by a fall in the infant mortality rate, which drops much more quickly in the urban setting.

Under pressure from these various factors of population growths, city limits creep irresistibly outwards, swallowing up the surrounding agricultural land from which the cities draw their food supplies.

In the industrialized countries, the expansion of the large cities has no significant effect on agricultural production, which is often in surplus. In the developing countries, on the other hand, this creeping expansion has a disastrous effect on the environment, on resources, on the geographical spread of the population and on social and professional structures. A striking example of this can be seen in the urbanization of 500 hectares of fertile land every year in the Nile delta owing to the expansion of the Cairo conurbation.

This excessive expansion of the big cities involves the construction of complex communications networks which are a heavy burden on shaky economies. Long and costly commuter journeys weigh heavily on the limited budgets of households forced out to the distant suburbs by the high rentals and living costs of city centres.

Controlling urban growth

Reduction of natural population growth rates in the developing countries--by action to influence birth and fertility rates as well as mortality and morbidity rates-figures high on the list of national and international priorities.

Without minimizing the importance of this objective, the urgent need to curb urbanization in the developing countries and to bring it into line with policies for agriculture, employment and population distribution also needs to be emphasized. If urbanization and the mass exodus from the rural areas continue unchecked, there is a danger that a slowdown in population growth may of itself lead to a fall in agricultural production and an upsurge of unemployment in the cities.

The urban cities and the social, technological and economic problems it brings in its train are acting as a brake on the economic advance of the countries of the Third World . It must be perceived as a worldwide process that requires concerted action. The measures adopted should be designed to promote the maximum development of the economic potential of the country concerned, especially in the rural areas. The aim much be to attempt to equate more closely the productivity per head of the population in the various regions by making the most of the natural and human resources at their disposal.

An effort should be made to rectify the excessive concentration of infrastructures, economic activities and services in the big towns and cities and to create industries and intermediate areas of activity to absorb rural manpower. Education and training or rural populations, especially the younger are groups, is essential if unemployment and disparity of earnings, which are among the main causes of the rural exodus and the over-population of the towns, are to reduced. In short, rural development should be integrated into national development by closer collaboration between local communities and the public authorities at the highest level.

MEHDI, AMANI, of Iran, is an adviser on population and development. A former professor of demography and dean of the social sciences faculty at the University of Teheran, he has also been a tutor at the French National Institute of Demographic Studies (INED) in Paris and a project leader in Africa for the United Nations Population Funds (UNFPA). He is the author of several books and articles on the teaching of demography and on problems of population and development in Third World countries.

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