We'll trade mexico for Canada.  Ownership isn't a problem, just gotta tell Mexico that they all get citizenship and all the benefits thereof if they just agree to be the 51st state.  Turning them into Canadians would be a dirty trick I agree, but Canada needs some southern beaches and we could use some more oilfields, Caribou, and highflow toilets so who cares what a bunch of Canadexicans think anyhow?