Sixty-eight years ago today, Johnny Cash played his first-ever prison concert and unknowingly changed the country music world.

On January 1, 1958, Johnny Cash walked through the gates of San Quentin State Prison and performed for inmates.

Cash was inducted into the Country Music Hall of Fame and the Rock & Roll Hall of Fame. He spoke to Fresh Air in 1997 about his career, from touring with Elvis to singing at prisons. He died in 2003.

If you know anything at all about the Man in Black, it's likely about his outstanding contributions to country music (and the music industry in general). But what you may not know about Johnny Cash is ...