''HAROLD & Kumar Go to White Castle,'' the road-trip film that opened last week, is the second movie this year to revolve around a fast-food chain. The first, of course, was ''Super Size Me,'' the documentary in which the filmmaker Morgan Spurlock lived, to ill effect, on nothing but McDonald's fare for a month.

''Super Size Me'' drew extensive attention for its supposedly novel concept, but its central gimmick was used more than 70 years ago by none other than White Castle. Back in 1930, the chain arranged for a medical student to live for 13 weeks on nothing but its hamburgers, and water. Edgar Waldo Ingram, one of White Castle's founders, later asserted, ''The student maintained good health throughout the three-month period and was eating 20 to 24 hamburgers a day during the last few weeks.''

That stunt is just one instance among many in which White Castle was ahead of its time. Few people seem to realize that White Castle was America's original fast-food chain: its first outlet opened in 1921, 27 years ahead of McDonald's. Indeed, White Castle was the key player in turning the hamburger into America's national meal.

Despite its significance in the nation's culinary history, not to mention several noteworthy marketing innovations, White Castle gets little respect, even by fast-food standards. Its little square burgers and turreted restaurants have become something of a pop-culture punch line, stuck somewhere between white-trash chic and ironic kitsch. Even the title premise of ''Harold & Kumar'' carries a wink-wink undercurrent of absurdity.