Why don't we just hand the country over to Mexico and points south? No, wait, the rest of the world wants a piece of us, too, and there's not enough to go around.
Ever read the book Civil War II? I'm told the author believes Mexico WILL reclaim the Southwest, ca. 2020.
Incidently, that's about exactly the time I'll be eligible to run for president. I'll run on a platform of "Manifest Destiny."