Youngstown, Ohio, the Golden Dawn Tavern.
Jonesborough, Tennessee, Gayle's Restaurant (especially good for breakfast).
Troy, New York, the North Troy Tavern.
Schenectady, New York, Jumping Jack's. (Technically across the Mohawk River in Scotia, this is a summertime only, old-fashioned drive-in. They call out the orders in their own code. Be sure to tip them.)
And for the best..Mount Vernon, Illinois, Opal's Smorgasbord. People on a low-fat, low-sodium diet shouldn't even drive down the street past the place.