The Louisiana Purchase was the 1803 agreement that transferred a vast territory from France to the United States.
The United States agreed to pay 15 million dollars for the Louisiana Territory, which covered roughly 828,000 square miles west of the Mississippi River. The transfer more than doubled the country’s size and gave the United States control of the Mississippi River’s lower course and the port of New Orleans.
President Thomas Jefferson authorized the negotiations, while Robert Livingston and James Monroe represented the United States in Paris. Napoleon Bonaparte’s government sold the territory partly because war in Europe made a North American empire less attractive and less practical for France.
The purchase did not instantly settle every boundary question. The United States and Spain later negotiated the Adams–Onís Treaty, and the acquired land was gradually organized into territories and states. The deal is therefore not the same as the 1819 treaty or the later Gadsden Purchase.