The Louisiana Purchase nearly doubled the territory of the United States in 1803.
The agreement transferred the vast Louisiana Territory from France to the United States. President Thomas Jefferson wanted control of New Orleans and the Mississippi River, which were vital to western farmers and merchants. French Treasury Minister François Barbé-Marbois offered the entire territory during negotiations with American diplomats Robert Livingston and James Monroe.
The United States agreed to pay 60 million francs, commonly described as $15 million, including the assumption of certain claims by American citizens against France. The land stretched from the Mississippi River to the Rocky Mountains, although its western boundaries were not precisely defined at first.
The purchase included all or part of 15 present-day U.S. states and two Canadian provinces. It is sometimes confused with the Alaska Purchase of 1867, which was a separate acquisition from Russia and occurred much later.