We did two trips to Calif. from Iowa, once through the Arizona desert and once down through Utah and Nevada in a brand new '56 Chevy Bel-Air without a/c. My parents drove at night when it was cooler(?) with the windows open.
My dad did it in a '32 Ford back in the late 30's with two friends. With no back seat they had to take turns in the rear, uncovered rumble seat!
Fantastic image. Did you ever see an window air conditioner? It was one that you putting water in it. We always carried two water bags on the front of the car. My dad a '50 merc, 52 merc and a '56 merc. When you are young. You only remember bits and pieces of the trip. Great trip down memory row.