land bought by the U.S. from France in 1803 for $15,000,000: it extended from the Mississippi to the Rocky Mountains & from the Gulf of Mexico to Canada
See Louisiana Purchase in American Heritage Dictionary 4
A territory of the western United States extending from the Mississippi River to the Rocky Mountains between the Gulf of Mexico and the Canadian border. It was purchased from France on April 30, 1803, for $15 million and officially explored by the Lewis and Clark expedition (1804-1806).