Everything south of the Mason-Dixon line is inhabitable only through air conditioning. everything south of the Mason Dixon line and west of the Mississippi is only inhabitable through air conditioning and irrigation. The desert southwest is full of Native American tribes primarily because they were driven off their ancestral lands and given desert shitholes that nobody wants; show me a reservation and I'll show you a swath of land that nobody wants to develop.
It's not going to continue forever. The New Mexico of my childhood has been replaced by the Arizona of my childhood and the Colorado of my childhood was the New Mexico of the past. The desert is winning.