It’s precious. Variety “slanguage” used the expression legit to reference legitimate (live) theater. Not movies, not vaudeville, not burlesque, not off-off, but bigly stuff, like Shakespeare or O’Neill. An example, “Choreographer Michael Kidd distinguished himself in legit before working in pictures.”
You’ve heard of Michael Kidd the “terpser”? right? He’s the guy who directs the “struts.” Again, Variety-ese.
In this news item dated May 25, 1938, we learn that 14 Broadway houses are being equipped with air-conditioning (“icing”) and that the newly “iced” “legit” houses will experience an uptick (“heat”) of ticket sales at their box office (“b.o.”)
So good! Who wrote that headline?