History: American Old West, United States

Through treaties with foreign nations and native peoples, political compromise, technological innovation, military conquest, establishment of law and order, and the great migrations of foreigners, the United States expanded from coast to coast (Atlantic Ocean to Pacific Ocean), fulfilling advocates' belief in Manifest Destiny. In securing and managing the West, the U.S. federal government greatly expanded its powers, as the nation evolved from an agrarian society to an industrialized nation. First promoting settlement and exploitation of the land, by the end of the 19th century the federal government assumed stewardship of the remaining open spaces. As the American Old West passed into history, the myths of the West took firm hold in the imagination of Americans and foreigners alike.
The term "Old West"
The American frontier moved gradually westward decades after the settlement of the first immigrants on the Eastern seaboard in the 17th century. The "West" was always the area beyond that boundary. Scholars, however, sometimes refer to the Old West as the region of the Ohio and Tennessee valleys. Most often, however, the "American Old West," the "Old West," or "the Great West" is used to describe the area west of the Mississippi River during the 19th century.