I would agree with that simply because the Mafia is really only found in a handful of areas today - mainly in the Northeast, Chicago and South Florida. Though the mob's bookmaking networks still extend to a lot of places and you still see bookmaking cases in areas where there is no real family left.

Some time ago I read a study on gambling that talked about how the Northeast is the biggest market for illegal gambling by far and indictments definitely bare that out. And most of the bookmaking cases in the Northeast are mob connected.