<P> The Louisiana Purchase was by far the largest territorial gain in U.S. history . Stretching from the Mississippi River to the Rocky Mountains , the purchase doubled the size of the United States . Before 1803 , Louisiana had been under Spanish control for forty years . Although Spain aided the rebels in the American Revolutionary War , the Spanish did n't want the Americans to settle in their territory . </P>
what did the louisiana territory do to the size of the united states
the purchase doubled the size of the United States