This is a picture from Shorpy, one of the great websites of all times. It features hi-res photos from around the turn of the Twentieth Century.
Take a look at this photo fully enlarged. I defy you to find a single person who is not wearing a hat or cap (or waving one).
|no clicking; go to the link above|
Damn that Kennedy: Bay of Pigs, Vietnam escalation, and the Decline of Hats. . . .