Here’s a map of America indicating whether people say “pop”, “soda”, or “Coke” to reference a soft drink. (In Singapore, we say “soft drink”. Or at least I do.) I knew “soda” was an East Coast / Left Coast thing, and that “Coke” was a southern thing (its Atlanta origins presumably contributes to some of that), but there’re pockets of “soda”-sayers in St Louis and Wisconsin, which intrigues me.
Incidentally, the home page references my old prof and friend Bert Vaux’s dialect survey.