The "Old Southwest" is an informal name for the southwestern frontier territories of the United States from the American Revolutionary War (1775–1783) through the early 19th century, at the point when the territorial lands were organized into states. The territory of the Old Southwest eventually formed the states of Missouri, Mississippi, Arkansas, Alabama, Louisiana, Texas, and parts of Tennessee, Kentucky, and Florida (panhandle). Geography Historians usually describe the Old Southwest as bounded by the Ohio River to the north, the Gulf of Mexico to the south, the Red River of the South to the west, and to the east, the western boundaries of Virginia, North Carolina, and Georgia. Much of northern, western, and southern Georgia is part of the Old Southwest, as the state did not grow into its modern boundaries until 1827. Some authors set the northern boundary of the Old Southwest at the Tennessee River rather than the Ohio. In the field of literature, the term is used to reference the Appalachian regions of the Southeastern states as well. Historians usually include West Florida in the Old Southwest, but the peninsula of Florida, or "East Florida," is often excluded. The Appalachicola River was the boundary between the Spanish provinces of West Florida and East Florida until 1820. The Florida Parishes of Louisiana, lying east of the Mississippi, were originally part of the Old Southwest. The Louisiana Purchase in 1803 added the city of New Orleans to the region. History The Old Southwest includes the homelands of numerous American Indian nations, including the Cherokees, Choctaws, Creek Nation, and Shawnee Nation. The European monarchies of Spain, Kingdom of France, and Kingdom of Great Britain competed with one another for territory and the allegiance of Indian leaders. In 1763 France made peace with Great Britain, following the French and Indian War, by surrendering all its territorial claims east of the Mississippi River. The British government soon reserved all the land west of the Appalachians for Indians, but many colonists defied the order and occupied parts of the territory. After the American Revolutionary War, in the Treaty of Paris of 1783, Britain ceded most of its North American territory to the United States, while Spain, a U.S. ally, took over in West and East Florida. In 1787 the United States Congress organized the Northwest Territory and established rules for founding new states, but the Old Southwest proved more difficult to manage. The