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

In the United States, the frontier was the term applied by scholars to the impact of the zone of land beyond the region of existing European occupation. 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 caused by land scarcity, and wastefulness of natural resources.

Operating in tandem with the doctrine of "manifest destiny", the "frontier" concept also had a massive impact on Native Americans like the declaration of terra nullius^[1] enacted by the British around 1835 to legitimize their colonization of Australia. The idea implicitly negated any recognition of legitimate pre-existing occupation and embodied a blank denial of land rights to the indigenous peoples whose territories were being annexed by European colonists.

Throughout American history, the expansion of settlement was largely from the east to the west and so 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.

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.

British, French, Spanish, and Dutch patterns of expansion and settlement were quite different from one another. Only a few thousand French migrated to Canada; the habitants settled in villages along the St. Lawrence River, built communities that remained stable for long stretches, and did not leapfrog west the way that the Americans would. 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 those areas was limited to a few very small villages on the lower Mississippi and in the Illinois Country.^[2]

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 but did not push westward.^[3]

In contrast, the British 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 British settlements were quite compact and small: under a square mile. Conflict with the Native Americans arose out of political issues on who would rule. Early frontier areas east of the Appalachian Mountains included the Connecticut River Valley.^[4] 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. The Americans began moving across the Appalachians into areas such the Ohio Country and the New River Valley.

After victory the American Revolutionary War and the signing Treaty of Paris in 1783, the United States gained formal, if not actual, control of the British lands west of the Appalachians. Many thousands of settlers, typified by Daniel Boone, had already reached Kentucky and Tennessee and adjacent areas. Some areas, such as the Virginia Military District and the Connecticut Western Reserve (both in Ohio), were used by the states as rewards to veterans of the war. How to formally include the new frontier areas into the nation was an important issue in the Continental Congress in the 1780s and was partly resolved by the Northwest Ordinance (1787). The Southwest Territory saw a similar pattern of settlement pressure.

For the next century, the expansion of the nation into those areas, as well as the subsequently-acquired Louisiana Purchase, Oregon Country, and Mexican Cession, attracted hundreds of thousands of settlers. The question of whether the Kansas Territory would become "slave" or "free" helped to spark the American Civil War. In general before 1860, Northern Democrats promoted easy land ownership, and Whigs and Southern Democrats resisted the Homestead Acts for supporting the growth of a free farmer population that might oppose slavery and for depoulating the East.

When the Republican Party came to power in 1860, it promoted a policy of a free land, notably the Homestead Act of 1862, coupled with railroad land grants that opened cheap (but not free) lands for settlers. In 1890, the frontier line had broken up; census maps defined the frontier line as a line beyond which the population was under 2 persons per square mile.

The impact of the frontier in popular culture was enormous, as shown in dime novels, Wild West shows, and after 1910 Western films that were set on the frontier.

The American frontier was generally the edge of settlement in the West and typically was more democratic and free-spirited in nature than the East because of the lack of social and political institutions. The idea that the frontier provided the core defining quality of the United States was elaborated by the great historian Frederick Jackson Turner, who built his Frontier Thesis in 1893 around the notion.

A Canadian frontier thesis was developed by the Canadian historians Harold Adams Innis and J. M. S. Careless, who emphasized the relationship between the center and periphery. Katerberg argues that "in Canada the imagined West must be understood in relation to the mythic power of the North" (Katerberg 2003). Innis's 1930 work The Fur Trade in Canada expounded on what became known as the Laurentian thesis: the most creative and major developments in Canadian history occurred in the metropolitan centres of Central Canada, and the civilization of North America is the civilization of Europe. Innis considered place to be critical in the development of the Canadian West and wrote of the importance of metropolitan areas, settlements, and indigenous people in the creation of markets. Turner and Innis have continued to exert influence over the historiography of the American and Canadian Wests. The Quebec frontier showed little of the individualism or democracy that Turner ascribed to the American zone to the south. The Nova Scotia and Ontario frontiers were more democratic than the rest of Canada, but whether that was caused by the need to be self-reliant on the frontier itself or the presence of large numbers of American immigrants is debated.

The Canadian political thinker Charles Blattberg has argued that such events ought to be seen as part of a process in which Canadians advanced a "border," as distinct from a "frontier," from east to west. According to Blattberg, a border assumes a significantly sharper contrast between the civilized and the uncivilized since unlike a frontier process in which the civilizing force is not supposed to be shaped by what it civilizes. Blattberg criticizes both the frontier and the border "civilizing" processes.

The pattern of settlement of the Canadian Prairies began in 1896, when the American Prairies had already achieved statehood. Pioneers then headed north to the "Last Best West." Before the settlers began to arrive, the North West Mounted Police had been dispatched to the region. When the settlers began to arrive, a system of law and order was already in place, and the Dakotas' lawlessness that was famous for the American "Wild West" did not occur in Canada. The federal government had also sent teams of negotiators to meet with the indigenous peoples of the region. In a series of treaties, the basis for peaceful relations was established, and the long wars with the Natives that occurred in the United States largely did not spread to Canada.

Like their American counterparts, the Canadaian Prairies supported populist and democratic movements in the early 20th century.^[5]

In the European Union, the frontier is a term used to describe the region beyond its expanding borders. The European Union has designated the countries surrounding it as part of the European Neighbourhood. That is a region primarily of less developed countries, many of which aspire to become part of the European Union. Current applicants include Turkey and Croatia, and Ukraine has also set itself the primary task of eventually joining EU, as have many small countries in the Balkans and the South Caucasus. Romania and Bulgaria joined the European Union in 2007.

Proposals to admit Turkey have been debated but are now currently stalled, partly on the grounds that Turkey is beyond Europe's historic frontier and is yet to comply with the 35-point policy that is set out by the EU. If all or most of Eastern European countries become members, the frontier may be the boundaries with Russia and Turkey.

• Cabin rights
• Marches

• The Frontier In American History by Frederick Jackson Turner
• Billington, Ray Allen. America's Frontier Heritage (1984), an analysis of the frontier experience from perspective of social sciences and historiography
• Billington, Ray Allen. Westward Expansion: A History of the American Frontier (1952 and later editions), the most detailed textbook, with highly detailed annotated bibliographies
• Billington, Ray Allen. Land of Savagery / Land of Promise: The European Image of the American Frontier in the Nineteenth Century (1981)
• Blattberg, Charles Shall We Dance? A Patriotic Politics for Canada (2003), ch. 3, a comparison of the Canadian 'border' with the American 'frontier'
• Hine, Robert V. and John Mack Faragher. The American West: A New Interpretive History (2000), recent textbook
• Lamar, Howard R. ed. The New Encyclopedia of the American West (1998), 1000+ pages of articles by scholars
• Milner, Clyde A., II ed. Major Problems in the History of the American West 2nd ed (1997), primary sources and essays by scholars
• Nichols, Roger L. ed. American Frontier and Western Issues: An Historiographical Review (1986) essays by 14 scholars
• Paxson, Frederic, History of the American Frontier, 1763-1893 (1924)
• Slotkin, Richard, Regeneration Through Violence: The Mythology of the American Frontier, 1600-1860 (2000), University of Oklahoma Press

• Blattberg, Charles Shall We Dance? A Patriotic Politics for Canada (2003), ch. 3, a comparison of the Canadian 'border' with the American 'frontier'
• Cavell, Janice. "The Second Frontier: the North in English-Canadian Historical Writing." Canadian Historical Review 2002 83(3): 364–389. ISSN 0008-3755 Fulltext in Ebsco
• Clarke, John. Land, Power, and Economics on the Frontier of Upper Canada. McGill-Queen's U. Press, 2001. 747 pp.
• Colpitts, George. Game in the Garden: A Human History of Wildlife in Western Canada to 1940 U. of British Columbia Press, 2002. 216 pp.
• Forkey, Neil S. Shaping the Upper Canadian Frontier: Environment, Society and Culture in the Trent Valley. U. of Calgary Press 2003. 164 pp.
• Katerberg, William H. "A Northern Vision: Frontiers and the West in the Canadian and American Imagination." American Review of Canadian Studies 2003 33(4): 543–563. ISSN 0272-2011 Fulltext online at Ebsco
• Mulvihill, Peter R.; Baker, Douglas C.; and Morrison, William R. "A Conceptual Framework for Environmental History in Canada's North." Environmental History 2001 6(4): 611–626. ISSN 1084-5453. Proposes a five-part conceptual framework for the study of environmental history in the Canadian North. The first element of the framework analyzes approaches to environmental history that are applicable to the Canadian North. The second element reviews historical forces, myths, and defining characteristics that pertain to the region. A third element of the framework tests the validity of Turner's Frontier Thesis and Creighton's Metropolitan Thesis when applied to northern Canada. The fourth element consists of an overview of major northern environmental trends. The final element consists of four interrelated themes that identify the environmental relationships between northern and southern Canada.

• Turner Thesis text
• Transhumanist.com: Opening Space as a Frontier