OK, this is awesome. The New York Times (whose infographics really are second to none) put together an index of searches from Allrecipes.com that maps out where queries for different Thanksgiving foods come from. Look at "green bean casserole" or "pumpkin cheesecake" and see exactly which states are searching for that dish.
Things to learn?
"Sweet potato casserole" was the most-searched term nationwide, but concentrated heavily in the South; Californians want to know how to make mashed potatoes; it's the Northerners who want to know how to brine a turkey. Of course, this raises the question: If something isn't highly searched in a given area, is that because fewer people are making it? Or because they already know how? It probably goes both ways. In any event, it's quite fun to scroll through.