When I was at Washington University in St. Louis, one popular and recurring conversation was about differences in dialect between different parts of the United States. This makes sense, as one of the main features of the school was that many people from the Northeast were living with many people from the Midwest, and there were large populations from the rest of the country as well. While there were a couple forms of this conversation, the most popular was, "What do you call carbonated sugary beverages, frequently served in aluminum containers, in your hometown?" Since this conversation was sort of annoying the first time I ever had it and was asinine the second through fiftieth time, I was happy to find this map which answers the question for all time. Also, the Missouri/Illinois border region is an island of "soda" in a sea of "coke" and "pop. Florida is interesting as well, possibly reflecting retirees.

If you want the numbers behind this map, follow the link under "map" above, I didn't steal all of their source. (Via Marginal Revolution, via Rasmusen.)