The American Old West (often referred to as the Old West, Wild West or Far West) comprises the history, geography, people, lore, and cultural expression of life in the Western United States, most often referring to the period of the later half of the 19th century, between the American Civil War and the end of the century. After the eighteenth century and the push beyond the Appalachian Mountains, the term is generally applied to anywhere west of the Mississippi River in earlier periods and westward from the frontier strip toward the later part of the 19th century. More broadly, the period stretches from the early 19th century to the end of the Mexican Revolution in 1920.
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 its 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 became a steward 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.