Air condition and sprawl
That the cities of the American South are vast, sprawling places thanks to their car dependency is wildly known . Metros like Atlanta, Charlotte and Greenville were small, peripheral cities prior to WWII and exploded in the decades after it. And when they did they were built to accomodate driving rather than walking or public transport. Though how much can you blame the car in itself and how much can you blame what makes it cool? I.e would they have been as sprawling if they had expanded in the decades when a growing number of people had cars but no good air condition?
Atlantic Cities lifts the importance of AC in the design of Southern cities and it would be interesting to see how much artificial cooling in cars benefited urban sprawl, since it’s not pleasant with long, slow, car-born commutes in 90 degree heat. If buildings can be designed to be naturally cool with “thick walls, porches, high ceilings and large windows” and it’s hard to prevent a car stuck in traffic on a clogged highway to cook its passangers alive, the shorter commute between a cool home and a cool office the better.