The Urbanization Process
It can be argued that urbanization represents the single most fundamental transformation of the twentieth century. Almost all other societal changes, for example, in levels of economic development, industrialization, the character of the family and fertility rates—indeed civilization itself—are contingent on the urban factor (Hall 1998). Although urban settlements—defined here as dense clusters of nonagricultural populations—have existed for perhaps 7,000 years, they seldom exceeded a few thousand people and only accommodated a very small proportion of the population of the territories they controlled.
In fact, it was not until after 1900 that any nation could be said to have a majority of its citizens living in urban areas. The industrial revolution in Britain, driven by the demands for a skilled and geographically concentrated labor force, and attracted by the economic benefits of agglomerating production facilities in dense settlements, produced the first truly urban nation in 1910 when more than 50 percent of its population was resident in urban areas. Other European nations followed soon after. The United States became predominantly urban, by this same measure, in 1920, whereas most Asian countries did not reach this stage until after 1945.
Prior to World War II less than 25 percent of the world's population was living in urban areas. Since then the process of concentration has accelerated, especially in the developing countries. By the end of the twentieth century roughly 48 percent of the world's six billion people lived in urban areas (United Nations 1996). Thus, the opening of the twenty-first century signals the beginning of another crucial global watershed: over 50 percent of the world's population will become urban dwellers.
Generally, the proportion of a country's population that is urban (i.e. the level of urbanization) is closely associated with the level of economic development—particularly the degree of industrialization—and the standard of living. In the advanced industrial economies today the urban proportion varies between 75 and 90 percent, in middle-income countries from 50 to 75 percent, and in the developing world from 10 to 50 percent. Recently, however, the long-standing association between levels of economic development and income per capita on the one hand and increases in the level of urbanization on the other has been broken. In many developing countries, unlike the industrialized world in the nineteenth century, the rate of urbanization has tended to out-pace the rate of economic growth. This has lead to a situation of over-urbanization, and the appearance of large mega-cities, often with insufficient employment opportunities, inadequate services, and intense poverty (Gilbert and Gugler 1994; Lo and Yeung 1998).