An evergreen chart here from the New York Times about a seasonal (in Minnesota anyway) amenity that has radically transformed our cities and homes for the better and for the worse.
Here is the chart showing the trend in the Midwest and other regions of the US:
I grew up in a house with central air, which seemed to me a wild luxury in the 1980s. But we rarely turned it on, maybe a week or two of the year. The rest of the time it was not necessary, and the windows were open.
That might be changing these days, though. Here is a bit of explanation and context about the a/c trends from the article:
Decades after air-conditioning made much of the Sun Belt livable, it has now become standard nearly everywhere. Eighty-six percent of new single-family homes in the Northeast are now built with it; 94 percent in the Midwest are. Parts of the United States whose historical development never depended on air-conditioning increasingly resemble the regions whose growth wouldn’t have been possible without it.
“Air-conditioning is reaching where it hasn’t reached before,” said Don Prather, the technical services manager with the Air Conditioning Contractors of America. “It’s been moving north and northwest, in every direction.”
…
“With the advent of air-conditioning, we lost a lot of the common sense,” said Kirk Teske, the chief operating officer at HKS Architects, with headquarters in Dallas. He worries that regions like the Northeast may lose it, too, setting up future challenges for office workers and residents when blackouts or other natural disasters come. “I sometimes say the best sustainably minded architects are all dead now,” Mr. Teske said. “They’re the ones that were able to do these big buildings knowing they had to do so without the benefits of air-conditioning systems.”
Despite Minnesota’s relatively moderate summers [knocking on wood], the Upper Midwest is no stranger to the central air conditioning unit and its companion (and raccoon-unfriendly) feature, the un-openable window.