Now that I've skimmed through my iTunes library, what is remarkable is how many more shows are set either "around the turn of the (20th) century" or more specifically between the year 1900 and World War I.
I'm sure some acute cultural critic like henrikegerman or Kad or Pal Joey will want to explain why the Edwardian Era holds such fascination for musical theater creators and audiences. Is it just that the decline and disappearance of the bustle frees up actresses so they can move?
The Beggar's Opera on which it's based is definitely set in the 1700's. Brecht is writing in the 20th century. So some revivals have landed on the 19th century as a compromise (like the great Raul Julia LCT revival in 1976).
But I always thought the intent was to keep it in the 18th century-- 1700's. Are there any lines/ lyrics that make the date more specific?
HARRIGAN AND HART (can't believe I forgot this one since I worked on it)
INTO THE WOODS Though God knows the costumes here straddle the 18th and 19th centuries-- Cinderella's sisters get panier skirts (18th cent.) but the princes are in 19th century dress uniforms. Hell, Jack and his mother come out of Breugel!