LAS VEGAS – Picture a perfect setting for college football and the scene probably involves fall foliage, marching bands, tailgate parties, and fans wearing school colors, singing fight songs, and strutting to the stadium en masse.

Or perhaps it involves expatriate alumni gathering at the sports bar to watch the game and revisit a slice of the campus life. Drop into a sports watering hold in New York on a Saturday afternoon and you’re likely to find packs of fans dressed head to toe in school colors, cheering their teams. The devotion to the school is driven by a shared experience and an attachment to the traditions that run so deep in college football.

The idyllic setting one imagines probably does not, however, include winding lines of anxious gamblers busily filling out their betting slips, waiting for the chance to slap their money down before the first game kicks off at 9 a.m.

But if you watch college football here in Las Vegas, that’s exactly the scene that materializes – and it’s driven by a devotion to a sometimes hidden aspect of the game that has made football, both college and the NFL, America’s true national passion.

That aspect is gambling, whether it’s a bet with the local bookie, an office pool, a parlay card found in a fraternity house, an offshore Internet account, or here, in the casino sports books. Only in Nevada can one legally gamble on professional and college team sports, and it’s done in nearly every casino on the Las Vegas strip.

The NCAA treats gambling as a profane word, and the NFL pays lip service to discouraging the practice (the league has turned down Las Vegas advertisements during Super Bowl telecasts). But both organizations know their sports’ popularity would not be nearly what it is without the willingness of millions of people to put a little something down on a game each weekend.

That is because football, by its nature, is the perfect gambling sport. Thanks to the point spread, which to a large degree transforms a game of skill into a game of chance, either team is an attractive proposition, even in the mismatches that dot the college schedule with such regularity.

Football is never far from the minds of many of the tourists who wander the Strip. On a fall Saturday, one finds packs of fans wearing jerseys, hats, and school t-shirts. Everywhere you turn, the day’s biggest games are playing on big-screen televisions. Score updates flash across the giant, neon casino marquees. All in all, it’s not that different from the atmosphere you’d find in a campus sports bar on a big-game Saturday.

But inside the sports book, the scene is somewhat different. Crowds envelop the big screens to follow the game, but the spread is never far from their minds. When Tennessee staged its second-half comeback against Notre Dame on Saturday, you could palpably sense the crowd regaining interest in what had been a ho-hum contest as Tennessee, a 8.5-point underdog, put itself in position to cover the spread before eventually losing 41-21.

The NCAA has in the past supported proposed legislation to ban legalized gambling on college sports. That legislation, supported by Senator McCain of Arizona, among others, has so far failed to gain traction in Congress, and although NCAA officials have been publicly disappointed, deep down they probably know that the continued existence of legalized sports gaming in Nevada is good for the sport.

Any form of gambling has the potential to threaten the integrity of the game if it invades the locker room or coaching box. NCAA history is dotted with embarrassing point-shaving scandals and other black eyes in basketball and football, most recently at Boston College and Northwestern.

But continued legalized gambling in Nevada has helped to expose far more gambling scandals than it has created. The casinos monitor betting on games so closely, in fact, that any unnatural move in the point spread – heavy money on one side or the other causes the pointspread to shift,in an effort to equalize the betting on both teams and ensure a win for the house – can spark an investigation. Abnormal betting patterns helped to expose a basketball point-shaving scandal at Arizona State in the 1990s.

The NFL, too, takes measures to ensure the accuracy of its point spreads. Teams are fined if they fail to provide timely, accurate injury reports. One of the major purposes of such reports is to protect the integrity of the point spread and prevent teams from withholding injury information that enterprising gamblers could be tempted to pay for.

The other reason the NCAA should abandon its efforts to end legalized gambling on its games is that Nevada sports betting represents but a small fraction of the wagering that goes on in college sports. Eliminating it would do very little to slow the overall amount of betting, and would only force more gamblers to seek other options for placing their bets – options that may not include the careful spread-monitoring done by the Nevada casinos.

Plenty of ink has been spent debating the pros and cons of legalized sports wagering, but the NCAA knows – as the NFL certainly does – that it should leave wagering alone because it helps drive interest in the sport.

One look around the Vegas Strip on fall Saturday tells you that. Those who come to cheer their teams do so for their own victory.

Mr. Levine is a writer for the statistical Web Site FootballOutsiders.com.