The Frontier Thesis or Turner Thesis is the conclusion of Frederick Jackson Turner that the wellsprings of American exceptionalism and vitality have always been the American frontier, the region between urbanized, civilized society and the untamed wildnerness. In the thesis, the frontier was seen as a region that created freedom, "breaking the bonds of custom, offering new experiences, [and] calling out new institutions and activities." Turner first announced his thesis in a paper entitled "The Significance of the Frontier in American History," delivered to the American Historical Association in 1893 at the World Columbian Exposition in Chicago.

Turner's thesis quickly became popular, especially since the U.S. Census of 1890 had officially stated that the American frontier had ceased to exist and westward movement would no longer be discussed in census reports. The idea that the source of America's power and uniqueness was gone was a distressing concept. Many, including future president Theodore Roosevelt, believed that the end of the frontier represented the beginning of a new stage in American life and that the United States must expand overseas. For this reason, some see the Turner thesis as the impetus for a new wave in the history of United States imperialism.

Further Reading

• The Frontier In American History by Frederick Jackson Turner