So who do you have today? The Broncos or the Seahawks? It’s the biggest sports betting day of the year, and there will be tons of high rollers in Las Vegas, New York and around the country laying money on the game or one of the many prop bets.

Here’s an interesting article on how the lines get set. High rollers of course already know how this works, but the article is pretty good at explaining it and also telling some good stories, like this one:

The handicapper predicts what team will win; the bookmaker doesn’t care who wins. So when Super Bowl XXIII rolled around and the San Francisco 49ers were a 7-point favorite against the Cincinnati Bengals, Gaughan — the man who revolutionized sports bookmaking in Vegas — decided to split the action.

You could have the 49ers at minus-6.5 or the Bengals plus-7.5 at Gaughan’s Barbary Coast property. He’d make the game attractive to both sides, drive as much money on the game as possible, and would likely win on either side. The only way he’d lose — and potentially lose big — was if the 49ers won by 7 and he had to pay both sides.

Going into the fourth quarter, the Bengals led the 49ers 13-6, with the game sitting on that disastrous 7-point margin. Two San Francisco touchdowns would have cost him $18 million.

It wasn’t until three minutes remained in the game, when the Bengals kicked a field goal to go up 16-13, that the game moved off a potential 7-point margin.

“I was in bed with the covers over my head,” Gaughan said. “I’d still be paying it off today.”

Check it out.