The United States agreed to pay France $15 million for the Louisiana Purchase in 1803.
French Treasury minister François Barbé-Marbois offered the entire Louisiana Territory to U.S. negotiators Robert Livingston and James Monroe for that sum. The treaty was signed in Paris on April 30, 1803, and announced in the United States on July 4. President Thomas Jefferson had initially authorized negotiations focused on New Orleans and its surroundings.
The purchase nominally covered about 828,000 square miles west of the Mississippi River and nearly doubled the country’s size. It did not simply transfer land that France densely governed; much of the territory was inhabited by Native American nations. The deal also raised constitutional questions because Jefferson had not clearly been given purchase authority.