In 1803, President Thomus Jefferson completed a treaty with the French government to purchase a large section of land in North America. This land is now known as the Louisiana Purchase. The purchase was important to the future of the U.S. It was the first major expansion of the U.S. since it had won its independance from Great Britain 20 years carlier. The tervitory gained in the Louisiana Purchase was the largest in U.S. history, totalling 828000 squares miles, about 23% of the current U.S. land area. The Louisiana Purchase also secured the U.S.'s right to passage along the Mississippi River and allowed access to the important port of New Orleans.