Two versions of this map, one showing survey details, the other aggregating by county.
The great pop vs. soda controversy is a project that Alan McConchie did to survey regional use of generic names for soft drinks. You’ll see here clearly that Michigan is a “pop” state; the sharp Wisconsin vs. Upper Peninsula divide of soda vs. pop is notable. You have to do pretty far south into Indiana to see “coke” as the generic.
Matthew Campbell from East Central University (Oklahoma) took this data set and organized it on county boundaries. Again Wisconsin vs. UP is clear on the soda/pop scale. I’ll attribute that to a difference in state law: it’s “pop” if you have to pay a 10 cent deposit on the can, and “soda” if you don’t.