When you have more people than a stressed environment can sustain ...
Exhibit A: Pueblo Grande and Snaketown.

Some years back I spent time with an old Phoenix attorney. To establish some temporal perspective, he was a contemporary and lifelong buddy of Barry Goldwater's, them having grown up together in early-20th century Phoenix. When he spoke of summers for a large chunk of his life that meant nights spent on sleeping porches and damp sheets hung to catch a breeze if one happened to appear. Otherwise, folks who could manage it took off for places up in the mountains like Prescott. He'd kept as cool as technology allowed, which mirrored that recalled by Indian Wars troopers in the SW, who filled large ollas with water, moistened the surface, and positioned them beside damp sheets hung to catch any movement of air.

When I hear of data centers and new mines proposed and developed in AZ, watch the ludicrous display at Fountain Hills, and recall it wasn't all that long ago the entire state - and a good deal more than that besides - was labeled "The Great American Desert," there's a visceral fear that just set a few more of my mind's floorboards to creaking.