In 1762, Louisiana was ceded to Spain as a result of the French and Indian War, and Great Britain gained control of Florida, which extended to the east bank of the Mississippi. At the same time, Acadians, driven from Nova Scotia by the British, began migrating to Louisiana. The Acadians settled in the eastern prairies around the present site of Saint Martinville and later along the Lower Mississippi and Bayou Lafourche.
The Spanish made feeble attempts to offset the growing French population, but were eventually absorbed themselves. In 1800 they returned Louisiana to France by the Treaty of San Ildefonso. Although Napoleon I originally intended to establish a new empire in America, he sold Louisiana to the United States in 1803. The $15-million Louisiana-Purchase represented about 4 cents an acre. Louisiana became the 18th state on Apr. 12, 1812, comprising the territory south of 33 deg North latitude, which had been the Territory of Orleans. The rest became the Missouri Territory. Not until 1819, however, were the Florida Parishes and the lands west of the Red River added to form the present state boundaries.