Pop, to my knowledge, is a Yankee term. I used to work for a man that called all soft drinks "Pepsi", while everbody else I knew said "Coke". 'Twas confusin'. I will occasionally hear someone speak of a "sody-water" (usually trying to be funny), but I have never heard anyone say "soda". But then, Arkansas is a fur piece north o'here. Mebbe they been infected by Yankee-speak.