Home > West's Encyclopedia of American Law > Louisiana Purchase

The Louisiana Purchase of 1803 doubled the size of the United States, gave the country complete control of the port of New Orleans, and provided territory for westward expansion. The 828,000 square miles purchased from France formed completely or in part thirteen states: Arkansas, Colorado, Iowa, Kansas, Louisiana, Minnesota, Missouri, Montana, Nebraska, North Dakota, Oklahoma, South Dakota, and Wyoming. President THOMAS JEFFERSON was unsure if the Constitution authorized the acquisition of land, but he found a way to justify the purchase.

France originally claimed the Louisiana Territory in the seventeenth century. In 1763 it ceded to Spain the province of Louisiana, which was about where the state of Louisiana is today. By the 1790s U.S. farmers who lived west of the Appalachian Mountains were shipping their surplus produce by boat down...