Well, the US is a big place, so it's not hard to find regional cuisines. They spread like the population does (it's not hard to find Buffalo Wings in Florida), but there are the chowders in coastal New England, BBQ (both dry and wet) in the south and midwest, Cajun & Creole in (what's left of) Louisiana, Alice Waters' "California Cuisine", "Soul Food" in the south, Tex-mex and other fusions (like Floribbean). There's also particular items that are known for being from the region: Pennsylvania Dutch scrapple, Pacific Northwest cedar plank salmon, Philly cheese-steaks, aforementioned Buffalo Wings, "American Chinese" like Chop Suey, Chicago deep-dish pizza, Maryland crabcakes. Each of these things, I think, stand alone as opposed to having simply been imported from somewhere else.
/jordan