When I was growing up in Southeastern Washington, we'd call a can of fizzy carbonated beverage a can of "pop." Here in SoCal, it's called a can of "soda." In many places, "coke" has become a generic term for the stuff, whether it's Coca-Cola or not.
Here's a chart of generic names for soft drinks, county by county. It confirms that soft drinks in my home county continue to be called "pop," while all of Southern California calls them "soda."
Thanks to Mark Evanier's blog for the link.