WOW! I see that this thread is a year old, but I was just told about it by my friend Alex Allan, who runs an exhaustive Grateful Dead lyric site: http://www.whitegum.com/intro.htm. He and I, along with our friends Matt Schofield (http://www.deaddisc.com/) and Dick Rosemont (http://www.originalsproject.com/) have been discussing the roots/earliest recordings of Dead songs for years now. "I Know You Rider" has always been one of the harder ones to pin down, and now I understand why. Bob, thank you so much for all the clarification.

I have a few points to add. It's true that the Kingston Trio, the Big Three, and Judy Henske all recorded the song for LPs that were released in 1963. If the January 1st date cited above is accurate, then clearly Henske's was the earliest of those three. I didn't know about the Baez or Aaron versions until reading this thread, so it's thrilling to learn about those.

There are two issues that are still troubling: The Big Three recording credits the song to blues legend Sonny Terry. I can find no indication that he ever recorded the song, but how do we explain the credit?

Bob, the only other possible precedent I've heard of--and it's a long shot, is called "I Told My Rider" by Robert Wilkins, recorded in September 1928, never issued and presumably lost (http://www.wirz.de/music/wilkifrm.htm). So even if that is a precedent, I don't think we'll ever be able to find out.

By the way, the Grateful Dead's earliest recording of the song dates from November 1965.

Anyway, just wanted to thank you for this thread, and add what little I could.