URBAN TRENDS IN THE TWENTIETH CENTURY
Just as nineteenth-century technology proved to be centralizing and to promote very great population densities, twentieth-century technology proved to be exactly the reverse. One decentralizing technology after another appeared on the scene, a process that continues to the present time. For perhaps about the first half of the twentieth century, technology favored decentralization within metropolitan areas but did not favor smaller over larger areas. Thus many large metropolitan areas grew rapidly, usually with the major share of growth occurring in their suburban areas.
Figure 2-1 shows the redistribution of population from 1900 to 2010. The figure is based on standard U.S. Bureau of the Census categories. Any point in the nation is located either in a metropolitan or in a nonmetropolitan area. Within metropolitan areas any point is located either in a central city, usually a place with a population of 50,000 or more, or in what the U.S. Bureau of the Census refers to as the "part outside" and what is referred to more casually as the suburbs. (This terminology has changed slightly for the 2010 census, as explained in the note for Figure 2-1.) The distinction between suburb and city is based on jurisdictional lines and thus may not correspond to what you would see on the ground. There may be many areas in the "part outside" that are urban in character; and, conversely, many parts of the central city may have a lower-density, suburban character. Across the century, the U.S. Bureau of the Census has designated new central cities and new metropolitan areas, and existing metropolitan areas have grown as new counties have been added on their peripheries. Thus the picture presented by Figure 2-1 is only a rough abstraction of a very complex situation. Nonetheless, it correctly depicts a massive change.
The distinction between suburb and city is based on jurisdictional lines and thus may not correspond to what you would see on the ground. There may be many areas in the "part outside" that are urban in character; and, conversely, many parts of the central city may have a lower-density, suburban character. Across the century, the U.S. Bureau of the Census has designated new central cities and new metropolitan areas, and existing metropolitan areas have grown as new counties have been added on their peripheries. Thus the picture presented by Figure 2-1 is only a rough abstraction of a very complex situation. Nonetheless, it correctly depicts a massive change.
FIGURE 2-1 U.S. population 1900 to 2000 by place of residence, in millions.
Note: The figures for 1900 through 1940 are estimated for 1950 Standard Metropolitan Statistical Area (SMSA) boundaries. From 1950 on, with each decennial census some SMSAs got larger as additional counties were added to them and some new SMSAs came into being as a function of population growth. Thus the trend lines up through 1940 and those after 1940 were not done on the same basis and are not entirely comparable. For 2010 the Bureau of the Census dropped the term central city and substituted principal city, distinguishing between principal cities in metropolitan and micropolitan areas, the latter term referring to smaller urbanized places within metropolitan areas. Data from the 2010 census have been adjusted to make them approximately comparable to earlier censuses. The apparent decline in nonmetropolitan population from 2000 to 2010 may be in part an artifact resulting from some areas that were classified as nonmetropolitan in 2000 being reclassified as metropolitan in 2010.
Sources: For 1950 and earlier, Donald J. Bogue, Population Growth in Standard Metropolitan Areas 1900-1950, Housing and Home Finance Agency, Washington, DC, pp. 11 and 13. For 1960 and subsequent years, the Statistical Abstract of the United States, 112th and earlier editions, and direct communication with the Population Division, U.S. Bureau of the Census.
Note how the suburban portion of the total population began to grow very rapidly from the first postwar census (1950) and continued to grow rapidly through the 2010 census. In fact, the suburban population of the United States is now larger than the nonmetropolitan and central-city populations combined.
For population, the big decentralizing force was the automobile. Its speed and flexibility of route and schedule were preconditions for large- scale suburbanization. The first vehicles appeared in the 1890s, but their numbers grew slowly, reaching about 5 million by 1915. About this time, mass production of Henry Ford's Model T began, and the number of autos in the United States increased rapidly, reaching about 25 million by 1930. It is no coincidence that the first great period of suburbanization in the United States began in the 1920s.
The truck bore very much the same relationship to retailing, wholesaling, and light manufacturing as did the automobile to population. It permitted wide-scale decentralization by freeing firms from the necessity of being near rail lines. Retailers could follow their customers, and manufacturers could follow the labor force, with far more freedom than would have been possible a few years earlier. The decentralization of wholesaling followed naturally from the decentralization of retailing, which in turn followed naturally from the decentralization of population.
Other forces also accelerated the process of suburbanization. Improved telephone communications made possible some decentralization of economic activity by reducing the need for face-to-face contact. The development of motion pictures and commercial radio broke the monopoly of central places of entertainment and thus increased the relative attractiveness of outlying residential areas. The invention of the limited-access highway in the 1920s proved also to be decentralizing. The first limited- access divided highway in the United States, and possibly the world, was the Bronx River Parkway in Westchester County, New York, completed in 1926. Parkways were originally envisioned as giving the urban middle class, with its newly acquired automobiles, access to the countryside. Their unanticipated but more profound effect was to make it easier to live in suburbia while working in the central city.
Suburbanization proceeded at a moderate pace during the 1920s and then slowed somewhat during the Great Depression of the 1930s. America's participation in World War II between 1941 and 1945 represented a brief break in the suburbanizing process. Residential construction, other than for war workers, was halted; civilian automobile production was suspended; and gasoline was rationed. When the war ended, the country entered a sustained suburban housing boom. In the first decade or so after the war, part of the force behind suburbanization came from accumulated demand from the low construction years between 1930 and 1945. But the process continued unabated for many years beyond the period, which could be explained by pent-up demand from the 1930s and 1940s.