A/C became available to the masses. In 1950, the state had 750K residents, today it has about 7 million. The population of Phoenix in 1950 was 106K, today it is over 1.5 million, with about 4.6 million in the metro area. Without A/C, chances are the population today would be much closer to 1950 levels than to today's actual levels.

I was born in Arizona and much of my family is still there, but you'd have to triple my salary to get me to go back. Between mid-May and mid-October, anyway.