This is the way it is in Washington State. When I was growing up it was pop. And back then I remember the store signs saying "Pop". It was that way through the 90s. Then soda started creeping in. Chain stores used "Soda" in their signage. Now it seems all stores do. People used soda more in conversation, particularly younger people. Even family members switched. When I asked some they claimed they couldn't remember using pop. I now jokingly tell people I'm on a crusade to save the Washingtonian linguistic heritage by proudly using pop.When I was growing up in Kansas, it was "pop" - but everywhere I've lived since then, it's been "soda". So, for me, it's now "soda".