A few observations, if I may.
If you used this map to indicate what is defined as “the South” by virtue of using “Coke” to mean any sort of fizzy soft drink, then West Virginia would be totally out. In fact all of Virginia is a little suspect (and I’m sure they’d be horrified to hear me say it, proud as they are of their roots). Whereas Texas, often not considered the South by those of us of Eastern persuasions, comes in firmly on the Southern team.
Do observe how Southern Florida is decidedly Yankee in their fizzy drink vocabulary. And who knew Kentucky would be so Midwestern? The influence of Ohio. What a shame. The little circle of “soda” around St. Louis is also fascinating. How did that come about?
Confession: up here in NYC I say soda. I conform. It’s just too confusing otherwise. Do forgive me, Southern friends!