At DGD's school run by the Quakers/Friends, they are allowed to wear costumes to school on Halloween, and have a school parade at the end of the day. Thanksgiving is called such on the school calendar, and the December holidays are called just that. Despite her school being run by a religious group, they are open to attendees from other religions and beliefs and the children learn what Hanukah, Ashura, Kwanzaa, Bodhi and Christmas ( as well as some other religious observances that she keeps teaching me about, LOL) means now and then. Some of her classmates wear hajibs, others yarmulkes (boys and girls), and one or two of the Christians, long dresses or skirts.
I love the progressive and all encompassing atmosphere and truly think if all took to the time to learn more of other religions the world would be a better place.
I don't recall being allowed to wear costumes to school in the "bad ol' 60's". Heck, girls, weren't allowed to wear pants until I was in jr h.s.
I seem to recall that my kiddos didn't wear them to school either and think that remembrance is accurate since I oft times was still making their costumes when they came home from school. I do know that my oldest nephew (about 6 years younger than my youngest) wore costumes to school though.