What 1803 agreement transferred a vast French territory to the United States?

The Louisiana Purchase was the 1803 agreement that transferred a vast French territory to the United States.

The United States acquired approximately 828,000 square miles from France for $15 million. The transaction was completed during Thomas Jefferson’s presidency and substantially expanded the nation’s territory west of the Mississippi River.

Napoleon Bonaparte’s government agreed to sell after French plans in North America weakened. The Haitian Revolution, renewed war with Britain, and the difficulty of defending Louisiana all influenced France’s decision. The purchase was formalized through treaties signed on April 30, 1803, and the transfer took place later that year.

The agreement raised constitutional questions because the Constitution did not explicitly describe a presidential power to buy territory. Jefferson ultimately supported the purchase, and Congress approved the funding. The land’s boundaries and Indigenous sovereignty remained sources of dispute for generations.