this land is now known as the 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 independence from great Britain 20 years earlier. The territory 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. right to passage along the Mississippi River and allowed access to the important port of New Orleans