URBANIZATION. The growth of cities has been charac teristic of modern industrial society, particularly since the 18th century. Since about 1920, however, there is a suggestion of a de crease in the rate of urban growth. This movement from rural to urban places has affected the entire social order of the modern world. In turn, this movement has been largely occasioned by changes in the basic economic structure of society—that is, the change from hand to power-driven machine production.
The changes in urban-rural distribution of population have been statistically measured in most of the prin cipal nations of the world. Most major countries have taken cen suses of population since 1930, but the definition as to what con stitutes an urban community has not been uniform from one country to the next. The population of the world in 1937 was placed at about 2,000,000,000. The nations which do distinguish between urban and rural areas had an aggregate population of about 927,000,000, of whom about 332,000,000, or 36%, were classified as urban. The data for these countries are presented in Table I. (The figures given represent the populations of the sev eral countries on the dates of the censuses quoted.) Notable in the process of urbanization has been the growth of the very large cities. There are probably 36 cities in the world that have popula tions above i,000,000. There are five such cities in the United States, three in Great Britain, twelve in other European coun tries, eleven in Asia, and five in countries elsewhere.
As defined by the census, urban territory in the United States includes all incorporated places of 2,500 in habitants or more. In 179o, there were only 24 such places, having an aggregate population of about 202,000, or 5% of the total popu lation. By 1860 urban places contained about 6,200,000 persons, or 2o% of the total population. By 1920 over one-half (51%) of the inhabitants of the United States were classified as urban.
The number of urban places in 1930 was 3,165, containing 69,000, 000 inhabitants, or 56% of the country's population. Conversely, the rural population decreased from 95% of the total population in 1790, to 44% in 1930. (See Table II.) In many instances the population of cities has been increased by the annexation of surrounding suburbs to the central city. In general, however, these cities have grown mostly through move ment to them of persons from rural areas.
The term "Metropolitan Region" is used to include the central city and its surrounding dependent suburbs. The city, in most instances, represents the focal point of the economic life of an area. The political boundaries of a city, on the other hand, have often been the results of historical accidents. Thus it is that present boundaries do not accurately designate that area which contains the urban population which a city repre sents, and in which the social and business life of the inhabitants of a city takes place.
Around most large cities cluster suburban districts which are as much a part of the social and economic life of the city, as is any part of the city itself.
In the United States in 1930 there were 96 metropolitan re gions, each having an aggregate population of ioo,000 or more, and each containing one or more central cities of 50,00o or more persons. Altogether about 55,000,000 persons, or 45% of all the inhabitants of this nation lived within metropolitan regions in 1930, as compared with about 40,000,000, or 38%, in 192o.
BiBuocRAniY.—United States National Resources Committee Publi cations, Problems of a Changing Population, Chapter III (May 1938) ; and Our Cities (June 1937) ; Lewis Mumford, Culture of Cities (i938). (L. E. T.)