How did geographic features influence the Louisiana purchase and the monroe doctrine?

Louis and Clark found the discoveries of the west staggering. They saw that the land was stable for future agriculture, and contained many mineral deposits. Seeing that the land was economically stable, they found the purchase to be a great deal. This lead to the Louisiana Purchase. Honestly (this is just my opinion), I don't think that geography had an impact on the Monroe doctrine, but the Monroe doctrine had an impact on those who settled since it

asserted that the Americas were not to be further colonized by European countries but that the United States would neither interfere with existing European colonies nor meddle in the internal concerns of European countries.