There was a story that the Carters frequently told about that song and when it was written. When AP was a young man he went North to work in the automobile plants so that he could provide for the family. Keep in mind that this is long before his marriage to Sara. While there he was treated terribly, life was terrible. He went back to his bunk, and wrote a song expressing how he felt and what he must do in life regarding his actions and thoughts. The result was Keep On the Sunnyside. Needless to say, AP stayed one more month then went back to Virginia to sell fruit trees. While selling trees he met Sara. That is just some folklore for you.