From the horse's mouth:

MOUNTAIN MAN: BILLY EDD WHEELER talks to Spencer Leigh
(This feature appeared in two parts in Country Music People, July and August 2005.)

"...The Coming Of The Roads, a song about the devastation caused by strip mining ... was recorded first by Judy Collins and then by Peter, Paul and Mary."

The Judy Collins recording was on her "Fifth Album" (Elektra, 1965), so that was the earliest. Not to say that there weren't more recordings; the quote above is part of a comment that it was Chet Atkins's favorite song of Wheeler's.

~ Becky in Tucson