Watch Series: Bluegrass Underground Released in (2011) - Season 4 produced by USA, The TV Series categorized in Documentary, Musical, and content rating TV-G with duration 30 min broadcasted as these networks PBS, Streamed at Putlocker & directed by Todd Mayo. A musical adventure series emanating from The Caverns in Tennessee's majestic Cumberland Mountains. Celebrating the diversity of America’s musical heritage with artists from the full spectrum of genres: Bluegrass, yes but also Americana, Country, Soul, Blues, Rock N Roll, Gospel, Folk, and everything between. - Season 4