LAS VEGAS — Every year, the Super Bowl seems to get bigger.

The television ratings tell that story. Last year, the Kansas City Chiefs’ win over the Philadelphia Eagles was viewed by 115.1 million people, making it the most-watched Super Bowl in history.

Betting on the Super Bowl is growing every year too. The American Gaming Association said 68 million Americans are expected to bet on Sunday’s Super Bowl between the Chiefs and San Francisco 49ers. That’s more than one in four Americans (26%) and it's up from last year when a little more than 50 million people bet on the Super Bowl.

Those bettors are wagering a lot too. The AGA estimate is $23.1 billion. That’s up from $16 billion last season.

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That’s a massive spike befitting of the site of the game, which will be held at Allegiant Stadium just off the Las Vegas Strip.

Many wagers on contests and square pools

Not all of that Super Bowl action will be traditional wagers.

While 42.7 million Americans are expected to bet at a traditional sports book online, a retail sports book or with a bookie, 36.5 million plan to bet casually with friends or part of a pool or squares contest, according to AGA.

It is the second straight year in which more traditional bets are expected than casual bets. That’s due to more states than ever having legal sports betting.

It used to be that many bettors would make the trip to Nevada to bet on and watch the game on TV. Now many of them can bet on the Chiefs or 49ers before they leave home and attend the game in Las Vegas.

Fairly even split between 49ers, Chiefs

The game has a good matchup for betting purposes. The 49ers are a small 2-point favorite at BetMGM over the Chiefs, who have gotten a lot of attention from early bettors.

The American Gaming Association expects a fairly small split among bettors. The AGA said 47% of bettors planned to take the Chiefs and 44% planned to back the 49ers.

Betting on the Chiefs or 49ers — or the over, the under, who scores the first touchdown, whether the coin toss is heads or tails or what color the Gatorade dumped on the winning coach will be — is going to be a huge part of this Super Bowl Sunday. The AGA expects it to be bigger than ever, with a huge increase for the second straight year.