Wisconsin actually provides an intersting split in the "pop" and "soda" usage in the Midwest. Most of the state of Wisconsin would call a carbonated beverage "pop". A local carbonated beverage company used a jingle with the lyrics "I want a pop. I want a Shasta" However, the metropolitan Milwaukee area uses "soda" much more often than "pop". There are actually several differences in dialects between Milwaukee and the rest of the state of Wisconsin that amuse college Freshman for at least one evening.
Also, if anyone else uses the word "bubbler" for water fountain, please respond to help me trace the Milwaukee dialect.