This guy, Gary Cristall, seems to be working on a history. There is not much text yet, but there are some outstanding images of the early stuff as you go from chapter to chapter. The most immediately interesting (given the discussion) is the original poster for Mariposa 1961. There they all were!!

And I'd totally forgotten about the Jewish camp scene (one of the Canadian links to Pete Seeger).

Check out:

http://folkmusichistory.com/outline/01.shtml

yours,

Peter T.