In the 1950s
central air conditioning
made slow market penetration across the United States
. There have been several books written how this forever altered the American lifestyle
. (Well, I don't know specifics, sorry.)
But I have seen several photographs of movie theaters
and bowling alleys
with large signs on the outside with these words:
It's cool inside!
These were usually written in large blue letters with little white faux snow on the edges. The impression made by these photos and the accompaning story was that these large community centers were the first to get central air and used it as a drawing card. (Time,Life magazines, etc).
In large parts of the South, especially small towns, these signs still remain posted in the windows of long closed theaters, restaurants, etc. A sad monument to the appliance that led to strip malls and the death of most of small town America.