The Louisiana Purchase was the 1803 land acquisition that more than doubled the United States, a major expansion in the history celebrated by America250.
The United States purchased the territory from France for $15 million. The agreement was signed on April 30, 1803, and the transfer was completed later that year. The territory covered about 530 million acres west of the Mississippi River, although its exact boundaries were not fully clear at first.
President Thomas Jefferson supported the purchase because control of the Mississippi River and New Orleans was vital to the young nation’s trade and security. The acquisition also opened a vast area to U.S. exploration, settlement, and later territorial organization.
The purchase did not instantly create new states. Much of the land was inhabited by Indigenous nations, and its incorporation into the United States brought prolonged conflict, displacement, and disputes over slavery and political power. The later states and territories created from the region developed over many decades.