As part of a treaty with Spain, the United States gave up that land in exchange for Florida.
What if we didn't give it away and got Florida just for a cash payment instead? Texas is part of the U.S. early on without a fight with Mexico. What now?
Other than the fact that Texas was not part of the Louisiana Territory to begin with?
In the Adams-Onis Treaty, the U.S. gave up its claims on that area.