There was a danger that settlers in the new United States going over the Appalachians and into the Ohio Valley would begin to think of themselves as a separate nation.
President Jefferson wanted to avoid that. Then, by chance he had a spectacular piece of luck. He was offered the area of French Louisiana for a tiny price.
Now he needed to see if he could control all of the land as far as the Pacific, and use that to unite the people of America. To do that he had to know what was out west.
That was why he sent the Corps of Discovery.
