France sold the Louisiana Territory to the United States in 1803.
President Thomas Jefferson authorized negotiations initially focused on New Orleans, a vital port at the mouth of the Mississippi River. French representatives instead offered the entire Louisiana territory, and U.S. negotiators accepted the larger deal.
The United States agreed to pay 60 million francs and assume claims by American citizens against France, producing a total cost commonly estimated at about $15 million. The purchase treaty was signed on April 30, 1803, and the transfer was completed later that year.
The acquisition covered about 828,000 square miles and nearly doubled the country’s nominal area. It included land that later became all or part of 15 U.S. states, although the exact boundaries and extent were clarified over subsequent years.