The Louisiana Purchase was a treaty signed on April 30, 1803, between the United States and France that doubled the size of the United States. The United States agreed to pay $15 million for land comprising the western half of the Mississippi River basin, including New Orleans, which gave the United States control of the Mississippi River and the port city of New Orleans. The Louisiana Purchase was a significant event in American history because it helped the United States become a continental power, opening up opportunities for westward expansion and manifest destiny.
