It's got nothing to do with religion, the Founding Fathers or war veterans.
It's not a day for giving thanks, reflecting solemnly or - puh-lease - fasting.
Super Bowl Sunday is about big-ness. Big couches, big-screen TVs and big vats of salsa. It's about beer, noise, gambling. It's about self-indulgence.
And yet, despite the brashness, the last Sunday in January is also a day of inclusion, open to men and women, boys and girls. You don't need to know your tight end from your end zone. As long as you're near the tube, you can partake.
So, as the big game reaches its 35th year, it's time to ask: Has Super Bowl Sunday become the perfectly secular national holiday?
"It is the American holiday," asserts Michael D. Bernacchi, marketing professor at the University of Detroit-Mercy, who for years has made a sub-specialty of studying the cultural aspects of the Super Bowl. "It's not based on anything serious. It has no religious or political anchoring. It's just celebration for celebration's sake. It's perfectly matched for our temperament."
This isn't just conjecture. The super-ness associated with Super Bowl Sunday has become as much a part of the American experience as political scandals and traffic jams. Even people who have never heard of Baltimore's Ravens will be partying hard and loud tomorrow. And there are statistics to back it up.
For example, California's Avocado Commission reports that 22 million avocados - enough to fill a football stadium more than a foot deep - will be mashed into 8 million pounds of guacamole on Super Bowl Sunday, making it the second-biggest avocado consumption day, behind Cinco de Mayo.
The American Institute of Food Distribution says the expected devouring of 14,500 tons of chips, 4,000 tons of popcorn and millions of pizzas makes Super Bowl Sunday the second-largest day of eating, behind Thanksgiving.
Sales double at 7-Eleven stores on that particular Sunday (and antacid sales jump 20 percent the next day).
It's by far the busiest pizza delivery day of the year, and many bars and restaurants are forced to take reservations.
Beer and liquor stores say only New Year's Eve sales compare to those of Super Bowl Eve, which is certainly a major reason why work-force surveys find that 6 percent of the nation's workers call in sick on Monday.
"It's a party day," said Bill Marshall, manager of The Liquor Store on Belair Road. "I mean, it's the party day."
Of special note for Baltimore fans in this year's liquor store aisles: Barcardi's "Purple People Eater" wine coolers.
Need more proof of the big game's growing status as major holiday?
Among its Super Bowl facts, the National Football League Web site lists that Super Bowl Weekend is one of the year's slowest for weddings.
Hallmark Cards Inc.'s research department calls the Super Bowl the biggest at-home party of the year, with an average Super Bowl party size of 17.
Sales of big-screen televisions jump fivefold in the week before the game, according to the National Electronics Dealers Association.
Indeed, Super Bowl Sunday is all about the boob tube, which glows and hums not during 3.5 hours of football, but for hour after hour of pre-game hype.
"It's become a major social gathering," said Warren J. Belasco, chair of the American Studies program at the University of Maryland, Baltimore County, and an expert on food and television culture. "But the sports are almost superfluous."
There are reasons for this. It's cold outside. The Christmas-New Year's holidays are a month gone. People are ready for a party. And the television set provides the hub around which friends and family can huddle.
Professors have studied this stuff, written papers and books on the deeper meaning of such an event. They wonder: Are its origins in the tribal campfire or the religious pilgrimage? Is it about the game or the TV?
Says Belasco: "It's a ritual of abundance and excess, coming at a rather grim time of year. But TV is really what American culture is all about. So it becomes this extended television experience. That, to me, is mind-boggling."
Half of the 10 most-watched television programs of all time are Super Bowls, according to Nielsen Media Research.
And advertising industry surveys are finding that more and more people watch the game solely for the commercials. It was up to 8 percent last year. For the commercials.
Also on the rise is female participation in the annual ritual.
Last year, more than 130 million Americans watched the Super Bowl; 46 percent were women. The Super Bowl now surpasses the Oscars as the No. 1 TV program watched by women.
Such growth is considered a major success by the advertising and marketing industries. Bernacchi calls the Super Bowl the "prize jewel" of the mass media world.
That's because the event first grew beyond the bounds of the football game, to become a daylong event, and is now swelling into a weeklong event.
ESPN has been offering reruns of previous Super Bowl games this past week, and CBS is offering an hourlong tribute to the best Super Bowl commercials. Meanwhile, those who can't afford a Super Bowl ad have been holding Super Bowl sales. Newspaper pages have been filed with retail ads for sales on couches and beer mugs, sporting goods and seafood, cigars and cars.
"The football game is almost incidental now," Bernacchi said. "It's an orchestrated holiday for celebration and nothing else."