Suburbanization is one aspect of the more general process of the expansion and spatial reorganization of metropolitan settlements. Settled areas that are beyond the historical boundaries of what have been considered cities but still are clearly functionally linked to the cities or may not be considered suburban. What is suburban is a matter of social definition. For example, when small cities are enveloped by the expansion of larger cities, at what point should they be considered suburbs, if they should be called suburbs at all? As some cities extend their boundaries outward, will the newly settled areas not be considered suburban if they are within the new boundaries?

Many researchers in the United States have chosen to adopt conventions established by the U.S. Bureau of the Census. The term "suburban" refers to the portion of a metropolitan area that is not in the central city. This definition...