Tonic is only a Boston area/eastern MA thing, too. It's soda in western MA.I've spent my entire life just outside of Boston and it's always been tonic. I have gotten in the habit of using soft drink since I've spent more and more time working with people who are not natives of Massachusetts and have been a bit puzzled by the generic use of tonic.
This is interesting. I live in St. Louis and everyone I know calls it soda. And if you look at the map that was done a few years ago, St. Louis is a bright red soda blob/island... I don't know how accurate this is anymore, but I would say St. Louis is definitely soda.Soda - Chicago suburbs
My daughter lives in St Louis and she said that everyone calls it Coke, no matter what carbonated beverage it is.