I'm sure this has already been covered, but I'll reaffirm the previous statements anyway.
Most of the US calls the sugary fizzy beverages "soda". I learned this the hard way when I went out East for the first time when I was younger. I called it "pop" and I got the "Ohhhh, you're not from around here are you. You must be from the midwest."
It is known as "pop" in the Midwest, but apparently no where else. Someone said not in Wisconsin, but I'd argue that. I've heard it referred to as pop quite often in Wisconsin in several different cities. It's also generally accepted to say pop in Illinois & Iowa.
All soda is "coke" in the south - even Mtn. Dew. I don't know why because it's fucking dumb, but it is what it is.