Well,
They are right about PA. The dividing line is somewhere around Altoona I think on that map.
I just started calling it both pop and soda because I have friends from places like Kitanning (god-awful small town outside of Pittsburgh) who always called it pop.
I noticed one other interesting aspect. Most of the Southeast calls it Coke. Could that have something to do with the fact that Coca-Cola is in Atlanta?
Mitch