What 1803 agreement transferred the Louisiana Territory from France to the United States?

The Louisiana Purchase was the 1803 agreement that transferred the Louisiana Territory from France to the United States. The United States agreed to pay $15 million, including the assumption of certain claims by American citizens against France.

President Thomas Jefferson authorized the deal, which was negotiated by James Monroe and Robert R. Livingston. The purchase covered roughly 828,000 square miles west of the Mississippi River, including the important port of New Orleans.

The acquisition nearly doubled the size of the United States and strengthened American control of the Mississippi River system. Its exact boundaries were not immediately clear, and later exploration and treaties clarified the extent of the new territory. The purchase is distinct from the 1867 Alaska Purchase from Russia.