This has been shown many times. Basically the lower populated areas of the country use pop. The better parts of the country call it a normal name.
Yes, it has been posted many times, but it also seems to go in one ear and out the other when it is refuted every time. It's useless. I don't just mean "ZOMG! It says that we say 'Coke' in GA when we totally do not (that too), but even the base assumption (that we all have and frequently use a specific word to refer to sweetened carbonated beverages) is wrong. Most say "drink" when there is no need to be more specific where someone from another region would most likely say "pop." Assuming that we always say soda or soft drink or Coke in the same context is incorrect.
It seems that people who say "pop" are almost trying to use it wherever they can and use it where there is absolutely no need to distinguish it from other drinks. It's actually kinda funny. I hear it so often when my family from WV comes to visit and very rarely was there a reason to say it instead of "drink" (IOW, where we would have said "soda"). Even the people claiming to say "soda" or "Coke" or whatever don't realize the the vast majority of the comparable times they do not use the word they just claimed to use. The question is asked as if they need to pick the similarly-specific word they would use to substitute without actually asking which they would use in the same contexts (ordering food, requesting beverages, etc).