Well, Frank, it's none other than John and Alan Lomax who said the songs are related, but I think the relationship between "900 Miles" and "Black Girl" is mostly in the tunes. Now, where does "In the Pines" fit in, or does it just share a line with "Black Girl"? I have to say this is not as direct a relationship as we've seen in other songs.
From what I understand, Woody Guthrie recorded "900 Miles" long ago, but it was the Cisco Houston recording of the song in a minor key that was popular during the 1960's. I haven't been able to find the Woody Guthrie recording, so I don't know how different his tune was.
-Joe Offer-