N231YE From , joined Dec 1969, posts, RR:
Reply 3, posted (8 years 1 week 5 hours ago) and read 2297 times:
I believe Pan Am pioneered this back in the '50s. Back in those days, women would "hog" the lavatories to do their make-up, and other passengers would be left to hold; you know. So Pan Am came up with a lavatory strictly for women.