frontier, in U.S. history, the border area of settlement of Europeans and their descendants; it was vital in the conquest of the land between the Atlantic and the Pacific. The importance of the westward movement of the population and the lure of the frontier were clear even to colonial writers and early U.S. historians, but the theory that the frontier was a governing factor (if not the governing factor) in developing a distinctive U.S. civilization was not formulated until 1893, when Frederick Jackson Turner presented his thesis.
Basically, Turner held that American democracy was shaped by the frontier, namely by the contest of the settler with the wilderness of the frontier. There the settler learned self-reliance, judged others by their abilities, strove to improve his or her lot, and grew distrustful of external authority and formal institutions. In short, the frontier molded an American national character that was individualistic and egalitarian. Turner's work stimulated a tremendous amount of research and writing on the history and meaning of the frontier.
There is no question that the process of peopling the West is a central theme in U.S. history, although not, perhaps, for the reasons Turner suggested. The cultivation of frontier lands provided food for the growing number of workers in Eastern cities; its mineral wealth and other natural resources aided industrialization; and the need to keep the East and West united led to a complex and efficient national system of transportation and communication. At the same time, the existence of barely settled lands helped preserve a rural tinge to America well into the 20th cent. Many studies have been devoted to the fur trade frontier, the mining frontier, the grazing frontier, and other types of frontier, but emphasis has been to a large extent on the solid achievements of the farming frontier and on the central United States.
See F. J. Turner, The Frontier in American History (1920); F. L. Paxson, History of the American Frontier (1924); W. P. Webb, The Great Plains (1931) and The Great Frontier (1952); R. A. Billington and J. B. Hedges, Westward Expansion (1949); H. N. Smith, Virgin Land (1950); L. B. Wright, Culture on the Moving Frontier (1955); R. A. Bartlett, Great Surveys of the American West (1980); R. V. Hine, Community on the American Frontier (1985); P. M. Nelson, After the West Was Won (1989).