The sports gambling industry is preparing for a record-breaking inflow of money as Americans bet on the Super Bowl.

A record 67.8 million American adults are expected to bet a combined $US23.1 billion ($A35.4 billion) on the match between the Kansas City Chiefs and San Francisco 49ers, the American Gaming Association (AGA) said last week.

So far, the highest wager at Caesars Palace in Las Vegas is $US1 million on the 49ers beating the Chiefs, according to Caesars Sportsbook assistant director of trading Adam Pullen.

"They're very passionate about their teams, the Bay Area fans, and they come over and they use their passion at the betting windows," Pullen said.

"You might get more people that maybe wouldn't bet, are going to throw a bet down, just because everybody knows it's here. So, yeah, records will be set."

The number of American adults planning to bet on the NFL's title game is up 35 per cent from a survey conducted last year by the trade group representing the US casino industry.

And the estimated value of wagers is well up from $US16 billion last year.

With the expansion of legal sports betting, the AGA said traditional Super Bowl wagers are expected to pass casual wagers for a second consecutive year.

Las Vegas native Robert Jansing, a 49ers fan, was putting his faith - and money - in favor of San Francisco at the Caesars Sportsbook.

"I don't bet a lot, but on the Super Bowl, I always do the Super Bowl ... biggest game of the year," Jansing said.

"And I won the last two. I bet on Kansas City last year and I bet on the Rams a year before, so we'll see how it goes."

According to the AGA, 42.7 million American adults plan to place a traditional sports wager online, at a retail sportsbook or with a bookie, up 41 per cent from 2023.

Meanwhile, 36.5 million plan to bet casually with friends, up 32 per cent from 2023.

The AGA also said bettors are nearly split on the outcome of the game, with 47 per cent planning to bet on the defending champions Chiefs, and 44 per cent planning to bet on the 49ers.