Where in the US is it as cool in the summer that most people don’t own AC’s?

I think what a lot of people not from the US don't understand is that we have extreme temperature ranges in most states. It's not that northern states (east of the Rockies specifically) are cool and cold and southern states are warm and hot, it's that northern states are cooler and colder for longer and southern states are warmer and hotter for longer. It's relative and it's a matter of degree to some extent but neither one is spared heat and cold. I used to live in Minnesota and one day there it got to 105° F (40.6° C). It could also get to -30° F (-35° C) in the middle of the night in winter. So that's a 75° C temperature swing from season to season (135° F). Houses here have to be built to withstand all of that. All those deluded Europeans who think we have flimsy houses don't understand the weather challenges here. They are extreme. Much of the reason for that is because the center of the United States is wide open geographically. It's easy for the cold Arctic air that develops in Canada to sweep down through the entire Eastern United States all the way to the Gulf of Mexico. There's no physical barrier to stop it. The converse is also true. Warm air from the south and the Gulf of Mexico can head north all the way to Canada, and there's nothing in the way to stop it. Europe has the Alps to cut the continent in half into a southern zone and a northern zone. In the US, all the land east of the Rockies can share the same weather both in the height of summer and the depths of winter. The north will be colder in the south will be warmer but they will both get significant warm and cold.