The United States, as a nation and as a culture, is relatively young by world standards; movement, change, and action have always characterized us. In the 19th century, we swept westward across the continent in a land colonization and settlement that was unprecedented in scale and speed. True, there had been earlier geographic spread from the original points of settlement along the Atlantic Coast, but it was in the 19th century that the flood tide was reached.
Today in the latter half of the twentieth century, we are engaged in another massive and rapid redistribution of population. Rural-urban migration is leading to a partial depopulation of more than half of the counties of the United States. Actually, the depopulation is greater and more serious than the available statistics suggest, for it is the young people who are leaving in greatest numbers. As the present aging population dies, the rural decline will be still swifter. To the extent that people are leaving rural areas for the cities, the United States is experiencing a concentration of population.
At the same time a decentralization of population is under way. Large numbers of people are moving out of the older city centers into the rapidly growing suburban areas. In this respect, as in many others relating to land use, the grain of the study, or the degree of refinement in the detail of inquiry, affects the results. At one scale or level, the dominant movement is toward cities; at a finer scale, the dominant movement is outward from the city center.
All of these population movements are highly differentiated by race, income, and age classifications. The U.S. developments have parallels elsewhere in the world, as rural people flock to cities and cities spread outward. In the United States, the automobile and the highway system have made the average citizen highly mobile, permitting residence in locations relatively remote from the place of work, and hence on the whole our suburbanization is more far-flung than elsewhere in the world.
One of the most important land use changes going on in the United States today is this suburbanization process. In the current jargon, suburbs are where the action is. Land transfers, conversion of land from one use to another, and marked changes in land prices characterize the suburban fringe, which in most cases extends beyond the actual settled areas for a few miles. Land speculators, land agents, land assemblers, developers, builders, financial institutions, insurance companies, public utility companies, and above all the buyers of residential property are engaged, under rules and programs laid down by various governmental organizations, in changing land from some open or relatively unused state to a developed and used one.