Flowing Data has made an impressive series of maps documenting Americans' taste in burgers. The big one, documenting the closest of seven major burger chains for various points across the country, is above. Because there are so many burger chains in America, it's useful to look at the maps of burger chains individually to sort out regional preferences:
What's fun about this map is how many regional burger places there are. Look at all of those Texas Whataburgers (the best burger in all the land). Look at the California In-N-Outs. Look at how the Midwest loves those gross White Castle burgers.
This map shows the great divide between Dairy Queen and Sonic. There's no need to pick a favorite here because both Dairy Queen and Sonic are delicious.