Its hard to choose one specific food because we have a vary large country with many different regions. Whats the main food in one region may not be the same as in another. The main food in Alaska probably isnt the same as the main food in the Southewst or North East. I will say, tho, that the hamburger tends to cross many regional, cultural and social boundaries. Can be found in the lowest greasy spoon diners to top end gourmet restaurants.