Johnny Cash wrote Walk the on April 2, 1956. It was Cash's first number 1 billboard hit! It was 17 on the US pop charts, and remained on the record charts for over 43 weeks. Walk the Line sold over 2 million copies. Johnny Cash wrote the song one night backstage while in Gladewater, Texas. As a newlywed, he wrote the song as a pledge of his new devotion. He said, 'The lyrics came as fast as I could write. I had it finished in 20 minutes.' People often wonder why he hums when singing this song. He says it's to get his pitch as the song requires several key changes while singing.