Today, almost 75 percent of U.S. homes have air conditioning, but here's a bit about it's beginnings:
At the turn of the 20th century, Willis Carrier, a 25-year-old experimental engineer, created a primitive cooling system to reduce humidity around a problem at a printing company's high-quality color printer. He used an industrial fan to blow air over steam coils filled with cold water; the excess humidity would then condense on the coils and produce cooled air. Not only did it solve the problem, but the cool air started to make people comfortable, and then the lightbulb went off.
Today, a U.S. household is more likely to have central air conditioning or a window unit than it is to have a dining room, garage or even a dishwasher.
The technology that was initially envisioned as a tool to enhance industrial productivity is now a near necessity for American homes and transportation.
Just a little bit of knowledge I wanted to share in case you're ever on Jeopardy.