A frontier is a political and geographical term referring to areas near or beyond a boundary, or of a different nature.

United States

In the United States, the frontier was the term applied by scholars to the impact of the zone of unsettled land outside the region of existing settlements of Europeans. That is, as pioneers moved into the frontier zone they were changed significantly by the encounter. That is what Frederick Jackson Turner called "the significance of the frontier." For example, Turner argued in 1893, one change was that unlimited free land in the zone was available and thus offered the psychological sense of unlimited opportunity, which in turn had many consequences, such as optimism, future orientation, shedding of restraints due to land scarcity, and wastefulness of natural resources.

Throughout American history, the expansion of settlement was largely from the east to the west, and thus the frontier is often identified with "the west". On the Pacific Coast, settlement moved eastward. In New England, it moved north.

'Frontier' was borrowed into English from French in the 15th century with the meaning "borderland," the region of a country that fronts on another country (see also marches). The use of frontier to mean "a region at the edge of a settled area" is a special North American development. (Compare the Australian "outback".) In the Turnerian sense, "frontier" was a technical term that was explicated by hundreds of scholars.

Colonial North America

In the earliest days of European settlement of the Atlantic coast, the frontier was essentially any part of the forested interior of the continent beyond the fringe of existing settlements along the coast and the great rivers, such as the St. Lawrence, Connecticut, Hudson, Delaware, Susquehanna River and James.

English, French, Spanish and Dutch patterns of expansion and settlement were quite different. Only a few thousand French migrated to Canada; these habitants settled in villages along the St. Lawrence river, building communities that remained stable for long stretches; they did not leapfrog west the way the Americans did. Although French fur traders ranged widely through the Great Lakes and Mississippi River watershed, as far as the Rocky Mountains, they did not usually settle down. Actual French settlement in these areas was limited to a few very small villages on the lower Mississippi and in the Illinois Country. Likewise, the Dutch set up fur trading posts in the Hudson river valley, followed by large grants of land to patroons who brought in tenant farmers who created compact, permanent villages. They did not push westward.

In contrast, the English colonies generally pursued a more systematic policy of widespread settlement of the New World for cultivation and exploitation of the land, a practice that required the extension of European property rights to the new continent. The typical English settlements were quite compact and small--under a square mile. Conflict with the Native Americans arose out of political issues, viz. who would rule. Early frontier areas east of the Appalachian Mountains included the Connecticut river valley. The French and Indian Wars of the 1760s resulted in a complete victory for the British, who took over the French colonial territory west of the Appalachians to the Mississippi River. Americans began moving across the Appalachians into areas such the Ohio Country and the New River Valley.