> But this isn't the first time I've heard "tonic" attributed to New England, either. Maybe an extreme regional thing, like on a town level rather than the metropolitan or state levels. Or it could be something from prior generations that has died out except for vestiges here and there. It's possible my grandparents once called it tonic, although they haven't for as long as I've been around.

I've only ever heard one person call it tonic. It was my wife's great-aunt, who lives in Hopkinton, NH. We drove up to her place for the afternoon, and she offered me a tonic. Took me a minute to figure out what she meant.

Maybe it is from a bygone era... my wife's great-aunt is in her late eighties...