By the year 2000, over half of the world's population will be crowded into 3% of the earth's land mass. This trend towards urbanization is divided unequally with 17 out of the 20 largest cities in the world being located in developing countries. Many of these countries face phenomenal growth of small and medium-sized municipalities.
Under present conditions and levels of technology, the continued expansion of large urban centres creates risks of physical, economic and social breakdowns with the most serious political consequences. In both developing and developed countries, urban growth has been accompanied by severe social and economic problems, some of which appear likely to worsen as overall population growth is accompanied by the trend toward greater urban growth.
In developed countries, problems of environmental deterioration (especially air and water pollution), traffic congestion, and other disamenities are encountered. In the developing countries, it is difficult to provide the minimum social services such as housing, water supply, sanitation, education, and medical facilities in the rapidly growing urban areas, or to absorb an ever expanding labour force into struggling urban economies. This results in a deterioration of environmental quality. In some countries, the growth of the cities is reducing land available for food production. In an average city there is no clearly recognisable structure or satisfactory layout. Most cities are built haphazardly resulting in a random character that confuses the identity of city communities, creates chaos in the pattern of land use, wastes resources and prohibits coherent patterns of any kind. Cities are not capable of providing neither intense activity in high density areas, nor intense quiet in low density areas.
The problems of the large cities of the developing countries are due largely to the fact that they have materialized ahead of any systematic movement towards modernization. Many of these cities formed transmission points from which raw materials and food were sent to the metropolises of Europe and North America, and to which manufactured goods returned. Lacking is the human and technical resources necessary to deal with the full range of urban development needs, also hampered by the dense "forest" of vertical and horizontal separations within often unmanageable national bureaucracies. Rapid population growth has increased the tendency of cities in developing countries to outgrow the resources of the economies they are supposed to nourish and support. The traditional range of public services, utilities and welfare services taken for granted in the cities of developed countries are not generally available to the inhabitants of most of the cities of developing countries; even less so in the rural areas. Lack of finance, infrastructure and skills at all levels contribute to this situation.
One of the overriding influences is at the policy-making level, where the application of priorities, based on the experiences of developed countries, has led to a misunderstanding of the urbanization process. Indeed, neither the historically conventional European city, nor the colonial city, which has been the main focus of large-scale urbanization in the rest of the world, is really well-adapted to developing countries at the present time. Nor can the largest industrial cities, for all their success in other spheres, be accepted as socially or culturally desirable models, most having conspicuously failed to adapt to modern conditions and frequently having become sprawling industrial centres of dreary anonymity. The city throughout the developing world is in one sense the sign and symbol of a development process that could break down completely in the near future. Life in the city is failing to make good deficiencies in literacy and job skills or to provide work which the illiterate and unskilled can do.
The world's urban population increased by about 30% from 1970 to 1980, from 1,350 million in 1970 (37.5% of world population) to 1,800 in 1980 (41.3%), but the annual rate of urban growth remained at 2.9%, as in the 1960s. Regional differences are significant, the percentages of urban populations in 1970 and 1980 being: Africa (22.9 and 28.9); East Asia (28.6 and 33.1); South Asia (20.5 and 24.8); Latin America (57.4 and 64.7); North America (70.4 and 73.7); Europe (63.9 and 68.8); Oceania (70.8 and 75.9); USSR (56.7 and 64.8). The rural population, although decreasing in percentage terms, also increased in absolute numbers, from 2,310 million in 1970 to 2,600 million in 1980. Large and increasing proportions of the world's urban population are concentrated in big cities, some of them of historically unprecedented size. By the year 2000 50% of the world's 6 billion people will be living in urban settlements, and there will be approximately 40 "megacities" (with populations of over five million) in the developing world; by contrast there will be just 12 cities of this size in the industrialized countries.
There is no precedent in history for an increase of this order of magnitude. It has led to a degree of urbanization which, relative to the level of development, was excessive, so that it may be properly referred to as 'hyperurbanization' or 'overurbanization'.
The process of urbanization must be understood as a basic condition for and as a functional consequence of economic, social and technological development. Agglomeration economies accelerate growth, access to markets being the most significant benefit of concentration, and indiscriminate efforts to avoid urbanization may only serve to delay development. The crucial issue is not the presence of the process by itself, but its quantity in relation to time and economic factors and its quality expressed in social and physical terms.