Troughout the world today, cities are growing faster than their rural hinterlands in population and in economic activity. Migration to the cities has long characterized many countries. But in recent decades it has been so rapid as not merely to absorb the natural increase of rural people but actually to reduce the population in many rural areas. This urbanization of the world is a complex demographic, economic, social, technological, and political process that has many ramifications and interactions.
Millions of poor people live in urban centers, in what those who do not live there call slums. There are many reasons why this type of urban growth is undesirable and should be discouraged by governments: people live in poverty; antisocial conditions flourish; political instability is encouraged; health hazards are created. Yet the inmigrants who live there have moved to these places voluntarily and would strongly resist returning to farms and small towns.
While the slum is a ubiquitous feature of modern urbanism, living at a high level of personal consumption is also a feature of the modern city. The vast majority of the productive enterprises of modern economies are in cities.
Today's urbanization is but the continuation and acceleration of a process long under way, and there is good reason to believe that it will accelerate and intensify during the coming decades. There is no need to review here the history of the city's development, but a few quantitative measures may be interesting and helpful. Hoyt has estimated that in 1800 only slightly more than 1 percent of the world's population lived in cities of 100,000 or more population; by 1930, the comparable figure was 11 percent; and by 1960, 20 percent.1 The proportion of the population living in cities of over 100,000 in 1960 was quite uneven in different parts of the world. Forty-two percent of Americans were located in such cities. In Europe, excluding the U.S.S.R., the proportion was 33 percent; in the U.S.S.R., 24 percent. Asia as a whole was only 12 percent urbanized, and Africa as a whole only 8 percent.
All demographic projections of population for the world as a whole, for each continent, and for each country envisage further striking increases in total numbers of people, even if population planning results in a marked future decline in the rate of increase. Much of this expected national increase in numbers will be located in the cities of the future. The scale of urbanization and the tempo of change are likely to accelerate; the problems, as well as the opportunities, arising out of such urbanization will likewise grow.____________________