Over half of the world's population is living in 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.
According to the World Health Organization: In 2014, the urban population accounted for 54% of the total global population, which is up from 34% in 1960. The urban population growth is ever increasing and is expected to grow approximately 1.84% per year between 2015 and 2020, 1.63% per year between 2020 and 2025, and 1.44% per year between 2025 and 2030.
Looking back the past 40 years, 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 were 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.
[Developing countries] Between 1950 and 1975 the population of cities in developing countries grew by 400 million people. It is predicted that between 1975 and 2000 these same cities will have grown by nearly 1,000 million. In 1960 there were eight cities in developing countries that had reached or exceeded a population size over 4 million compared to 10 cities of the developed regions. By 1980, there were 22 cities in the developing regions with more than 4 million population each, whereas in the developed regions there were only 16 such cities. So rapid was the urban growth rate in developing countries that it seems certain that if this trend continues the number of people living in cities will double by the year 2000. Projections suggest that the developing countries by that time will have about 61 cities of more than 4 million each, compared with about 25 in the developed regions. Eighteen cities in developing countries are expected to have more than 10 million inhabitants each by that year. In Sub-Saharan Africa alone the urban population growth rate averages an annual 8.5% in the 35 major capitals, which are doubling their inhabitants every nine years.
Because this growth is taking place against a background of low incomes, it has outstripped these countries' abilities to provide both accommodation and services. The result is a mushrooming of squatter settlements around the perimeters of vast cities. From 20 to 80% of the urban populations of various cities lived in these shanty towns. In most cities in developing countries, the pressure on shelter facilities and services has degraded the urban fabric. The housing used by the poor is decrepit and civic buildings are frequently in a state of disrepair and advanced decay. The same may be said of essential infrastructure services (transport, public conveniences, water supply, drainage, sewage).
Urbanization has been one of the most striking developments of the 20th century. In Africa, for example, only 5 per cent of the population lived in urban areas at the beginning of the century, about 20 per cent in the 1960s and about 35 per cent in 1995. Africa's annual urban growth rate is now the highest in the world, at more than 4 per cent (see graph). The urban population of the Asia-Pacific region, now about 35 per cent of the total population, grew by 3.2 per cent a year between 1990 and 1995, compared with 0.8 per cent a year for the rural population (United Nations Population Division 1997). About 70 per cent of the population of North America, Europe and Latin America now lives in cities, and worldwide 326 cities have populations of more than 1 million, compared with 270 in 1990 (WRI, UNEP, UNDP and WB 1996). In Western Europe (EEA 1998) and North America (WRI, UNEP, UNDP and WB 1996), in contrast with most other regions, there is a move out of large cities into suburbs and smaller urban centres.
[Developed countries] Europe's total population was 325 million in 1920, 490 million in 1984, and will perhaps be 513 million in the year 2000. Virtually all the increase is reflected in Europe's urban population: 150 million in 1920, but which may number 437 million at the century's end, while the rural population may undergo an appreciable decrease. Other more developed regions have been gaining population at an even faster rate than Europe, and again the tendency is for rapid urbanization to be accompanied by a decline in rural populations.