In the movie Casino (1995) both Sam and Nicky move to Las Vegas from "Back Home" where the bosses are. It is clear that they both started their career in in their "home" town.
Which city do they refer to when they say "Back Home"?
I believe it is either New York or Chicago.
At some point Nicky mentions that the bosses are 1500 miles away. Chicago is 1700 miles, so it might be Chicago. I only found that piece of information.