The Louisiana Purchase was a treaty in which the United States acquired approximately 828,000 square miles of land west of the Mississippi River from France for $15 million, doubling the size of the country. The land was purchased at a very low price of less than 5 cents per acre due to France's loss of territory in Haiti and Napoleon wanting to shift his empire to Europe to fund military campaigns. The purchase was important as it gave the U.S. control over vital trade routes and resources and prevented European powers from exerting influence over the territory.