Our favorite Uncle notes:

You can tell when you’ve hit yankee country. When the gas stations stop calling it “soda” or “soft drink” and start calling it “pop”.

Since I grew up in “yankee country” (by which I assume he means “the North,” rather than its true meaning, roughly 3/4 of greater NYC), but always called it “soda” (never pop), this puzzled me a bit. Also, if anything, in the South, people seem more likely to call it “Coke,” whether or not it actually is, than to call it “soda.” And then there’s the uniquely New Orleanian abomination: cold drinks. (Imagine a vendor shouting out “Ice cold cold drinks!”)

Anyway, that got me curious, and a quick Google turned up this:

Pop vs. Soda Map

Pop vs. Soda Map