Air conditioning for buildings was perfected in the late 1930s though
> its use grew very slowly. A couple of buildings built during WW II in
> DC were air conditioning, I don't know how people survived DC's hot
> humidity in non a/c buildings. Technical advances and efficiency in
> the early 1950s allowed it to be more widespread and home window units
> came out at that time.
If you grew up in the south and never had it you just dealt with it. But the south never really took off economically until central air showed up.
The border in general was the Mason-Dixon line or basically the KY, VA east west line.
I grew up in far western KY and if you look at it with Google earth you'll understand how humid it could get. My dad built our house in 56 (I was 2) and we had window units when I was small. We added central air around 61 or 62. Then we built a new house and moved into it in late 67. It was setup for a/c but the compressors were not there initially. (Money and all that.) When it got to August, 1968 and after about the 4th day of 98/98 (temp/humidity) at 4 am, we bought and installed the compressors. :)
Here in Raleigh, NC, I can do summers without AC but my wife keeps talking about divorce so we pay the bills. :)
[TELECOM Digest Editor's Note: Ditto here in the southeast corner of Kansas by the Oklahoma border. You would not believe how high the electric bill is all summer long, but it is absolutely required to survive. (At least, 'survive' in the life-style of the late twentieth- century which we have come to expect.) PAT]