I think human migration is a huge problem world wide, and I don't see any way North America can escape from that. I wouldn't think it was nearly the problem it is, if the numbers of people in the places where the migration is coming from was going down, but it isn't, not anywhere that I know of.

                So it's just a matter of people moving from places that are over populated to places that are not quite yet overpopulated, and soon will be.