It's easy to fall down any number of information rabbit-holes there, so allow us to point you in the direction of "The American Variety Stage, 1870 - 1920" collection , then creep a little further into the audio archives and enjoy wax cylinder recordings of some vaudeville routines and songs from the era.
Given these were recorded both for posterity and mass consumption, we can't help but wonder how many blue routines were deemed unfit for preservation. That's our loss.
