I would consider this guy one of the greats although probably considered more a bluegrass icon but IMO he crosses both genre's. A true American super talent.
"A beach is a place where a man can feel he's the only soul in the world that's real"
All good artists and all are played every day on WUMB 91.9 FM radio Boston and on line at www.wumb.org. However, you forgot a few (dozen) folk artists, beginning with the late Kate Wolf.