Who shot John and who laid the rail

My mother has said this expression for years, as well as my grandmother too. What is the origin of the expression "who shot John and who laid the rail"?

I hope someone knows!

I'll check my books and see if there is an origin listed. What I can tell you is that I first heard, "He has been mayor since 'who laid the rail,'" meaning a long time, when I came to Kentucky. "Who shot John" I heard on a movie and took it to mean an old argument. "Don't start that 'Who shot John.'"

[Exploration of "Who shot John" has been going on almost as long as ... well, as the original argument over who shot John. A wide-ranging review, with appearances by some of our favorite usual suspects, can be seen at this web-address: www.wordwizard.com

[It would seem more foolish than brave at thisd point to attempt to resolve the question once and for all. - Bac.]