I just came across an interesting post (on a fairly fascinating website, given my interests) about the linguistic divisions of the name for carbonated beverages in the U.S. Observe:
I live in the stark borderland between ‘soda’ and ‘pop’ that runs through central Pennsylvania. ‘Soda’ fanatics to the east, ‘pop’ fanatics to the west… perhaps as a result, it’s commonly called “sodapop” around here. If you can’t beat ‘em, join both of ‘em.