I've always thought that a better indication of "southern-ness" than the Mason-Dixon line is what I term, "The Beverage Line." If you order tea in a restaurant and it comes on ice in a glass, you're in the south. If your waitress asks, "What kind of coke do you want?" and she's offering Pepsi products, you're in the south. I'm in Louisville, KY, and I'm rather partial to Twinings Lady Grey, hot, two sweet n lows, maybe a slice of lemon. But my mother keeps a pitcher of tea in the fridge at all times, and I have been known to refer to my beloved Tab, or my son's Mountain Dew, as "coke."
Imagine my surprise to learn that science is on the case- at least, as far as Virginia is concerned. Check this out. Don't just read the text, go to the data as well. Fascinating stuff. Myself? I'd like someone to codify those variables for KY and Southern IN.