I think Polk added the most.
The Mexican Cession and Oregon Territory together are bigger than the Lousiana Purchase.
In relative terms?
Oh I see what you're saying - the Louisiana purchase doubled the nation at the time, whereas these two later aquisitions, though larger, were being added to a larger exsisting nation - therefore representing a smaller percentage gain.
A lot of all three territories is still pretty much empty even today.
Yeah, that's what I'm saying.