In the year 1803, the United States purchased the Louisiana Territory (approximately 828,000 square miles in North America) from the country of France for $15 million. The signing of the Louisiana Purchase treaty on April 30, 1803 (8 Stat. 200) [PDF] doubled the size of the United States and promoted further westward expansion.

This timeline examines the role of Congress in the Louisiana Purchase from 1802 to 1807, including ratification of the treaty, establishment of a territorial government, confrontation with Spain over boundary issues, and its limited role in the Lewis and Clark Expedition. The congressional documents contained within this timeline come from the American Memory collection A Century of Lawmaking for a New Nation and the digital collections at the Library of Congress.