The United States bought the Louisiana Territory from France for $15 million in 1803.
The Louisiana Purchase Treaty was signed in Paris on April 30, 1803, by Robert Livingston, James Monroe, and François Barbé-Marbois. President Thomas Jefferson had initially sought New Orleans and access to the Mississippi River, but Napoleon’s government offered the much larger Louisiana Territory.
The purchase nearly doubled the nominal size of the United States. Its lands eventually contributed to all or parts of fifteen present-day U.S. states and portions of two Canadian provinces, although the treaty’s boundaries were not perfectly clear at first.
The transaction is often compared with the Alaska Purchase, but the two deals involved different sellers, dates, and prices. Alaska was bought from Russia in 1867 for $7.2 million; Louisiana was bought from France in 1803 for $15 million.