The United States completed the Louisiana Purchase from France in 1803.
President Thomas Jefferson’s administration agreed to purchase the territory from Napoleon Bonaparte’s France for $15 million. The treaty was signed in Paris on April 30, 1803, and the United States took formal possession later that year. The acquisition covered about 828,000 square miles west of the Mississippi River, although the exact boundaries were initially unclear.
The purchase more than doubled the size of the United States and gave the nation control of the Mississippi River and the port of New Orleans. These commercial advantages were especially important to farmers and merchants west of the Appalachian Mountains. Jefferson nevertheless worried that the Constitution did not clearly authorize the president to acquire foreign territory, so the agreement raised constitutional questions.
The purchased land was home to numerous Indigenous nations, and the transfer between European and American governments did not erase their sovereignty or rights. The territory was later divided into states and territories, but the purchase did not instantly create a single settled region under U.S. control.