What divides the North from the South? Surely nothing so simple and stark as the Mason-Dixon line between Maryland and Pennsylvania. It should be something that reflects behavior and cultural norms. We might consider what the locals call a small stream. Is it a branch (southern) or a run (northern)? Appropriately, the battle referred to by the Union army as First Bull Run went by the name First Manassas Junction in the Confederacy.
Less obscurely, numerous maps have been made about the Soda/Coke boundary, south of which all carbonated beverages are termed “Coke” (we will pass over the abomination “Pop” with no further mention). As a native North Carolinian, I never called my (non-Coke) soft drink a Coke, so the Soda/Coke line never rang true with me. But I can vouch for the veracity of another beverage-centric line of demarcation: the sweet tea line. In the South, you can always count on being served sweet tea if you ask for “tea”.
The Romans stopped their northward civilizing advance into Europe wherever they could no longer cultivate grapes. It was bad enough being without olive trees, but a life without wine wasn’t worth contemplating. Perhaps Lee’s legions, stopping at a roadside inn near Gettysburg, felt the same way. “No sweet tea, boys. Let’s head on home.”
Rambles Blog at Star Chamber 
My Southern Mother, living in Penna., used to say that, to her, one of the most notable langage points was
“Greazy” (rhymes with easy,) vs “Greasy” (where the Grease pronunciation is retained.)