The universality of the automobile, even among the less affluent, and the parallel proliferation of service facilities and highways greatly loosened and fragmented the American city, which spread over surrounding rural lands. Older, formerly autonomous towns grew swiftly. Many towns became satellites of the larger city or were absorbed. Many suburbs and subdivisions arose with single-family homes on lots larger than had been possible for the ordinary householder in the city. These communities were almost totally dependent on the highway for the flow of commuters, goods, and services, and many were located in splendid isolation, separated by tracts of farmland, brush, or forest from other such developments. At the major interchanges of the limited-access highways, a new form of agglomerated settlement sprang up. In a further elaboration of this trend, many larger cities have been girdled by a set of mushrooming complexes. These creations of private enterprise embody a novel concept of urban existence: a metropolitan module no longer reliant on the central city or its downtown. Usually anchored on a cluster of shopping malls and office parks, these “hypersuburbs,” whose residents and employees circulate freely within the outer metropolitan ring, offer virtually all of the social and economic facilities needed for the modern life-style.
The new look of the metropolitan area
The outcome has been a broad, ragged, semiurbanized belt of land surrounding each city, large or small, and quite often blending imperceptibly into the suburban-exurban halo encircling a neighbouring metropolitan centre. There is a great similarity in the makeup and general appearance of all such tracts: the planless intermixture of scraps of the rural landscape with the fragments of the scattered metropolis; the randomly distributed subdivisions or single homes; the vast shopping centres, the large commercial cemeteries, drive-in theatres, junkyards, and golf courses and other recreational enterprises; and the regional or metropolitan airport, often with its own cluster of factories, warehouses, or travel-oriented businesses. The traditional city—unitary, concentric in form, with a single well-defined middle—has been replaced by a relatively amorphous, polycentric metropolitan sprawl.
The inner city of a large U.S. metropolitan area displays some traits that are common to the larger centres of all advanced nations. A central business district, almost always the oldest section of the city, is surrounded by a succession of roughly circular zones, each distinctive in economic and social-ethnic character. The symmetry of this scheme is distorted by the irregularities of surface and drainage or the effects of radial highways and railroads. Land is most costly, and hence land use is most intensive, toward the centre. Major business, financial and governmental offices, department stores, and specialty shops dominate the downtown, which is usually fringed by a band of factories and warehouses. The outer parts of the city, like the suburbs, are mainly residential.
With some exceptions—e.g., large apartment complexes in downtown Chicago—people do not reside in the downtown areas, and there is a steady downward gradient in population density per unit area (and more open land and single-family residences) as one moves from the inner city toward the open country. Conversely, there is a general rise in income and social status with increasing distance from the core. The sharply defined immigrant neighbourhoods of the 19th century generally persist in a somewhat diluted form, though specific ethnic groups may have shifted their location. Later migrant groups, notably Southern blacks and Latin Americans, generally dominate the more run-down neighbourhoods of the inner cities.
Individual and collective character of cities