> Which ones are in the cooler parts of the country

There are very few “cooler parts of the country.” Europe’s “no AC” culture was because, until the 2000s, almost everywhere had less than 15 days a year over 30C (85F). There’s only a handful of cities like that in the U.S., such as San Francisco and Seattle. Even in the northern latitudes the U.S. gets really hot. Cedar Rapids, Iowa, averaged about 50 85F+ days a year in the 1970s. Boston and Minneapolis were in the 30-60 range during that decade.

To put that into context, Germany over the last decade is seeing 15-20 30C+ days a year. It hit 30-31 only in two years recently, 2018 and 2019. Those years had 7,000-8,000 deaths each year. Germany’s epic heatwaves killing thousands of people was a mild summer in Cedar Rapids or Boston or Minneapolis even in 1970.

The U.S. is just a very hot country, even in the northeast and upper midwest. AC is a huge, lifesaving standard of living improvement almost everywhere in the country. And we shouldn’t take for granted the developments that enabled 88% of the country to have access to that technology.