March Madness remains the biggest betting event in the United States.

An estimated $3.1 billion is expected to be bet on this year’s NCAA men’s and women’s basketball tournaments with U.S. sportsbooks, a nearly 15% year-over-year increase and more than double the betting on the Super Bowl, according to research from the American Gaming Association released Thursday.

The AGA, a Washington, D.C.-based trade group, analyzed monthly revenue reports from state gambling regulators to form their $3.1 billion estimate. They estimated $1.4 billion would be bet on the Super Bowl in February.

Halvor Egeland, a trading manager for BetMGM, said the sportsbook is expecting betting handle on Round 1 of the men’s tournament to be similar to the Super Bowl.

“Super Bowl will certainly bring some bigger individual wagers than the tournament, but there’s no shortage of interest,” Egeland told ESPN. “March Madness is a massive time of year for us.”

The brackets for the men’s and women’s tournaments will be released Sunday. The AGA’s estimate does not include any money risked in office bracket pools.

“March Madness is one of the most exciting times in American sports, with fans fired up for both the men’s and women’s NCAA tournaments,” Joe Maloney, senior vice president of strategic communications for the AGA, said in the release announcing the estimate. “As legal wagering expands across the U.S., more fans than ever have the opportunity to bet legally and responsibly.”

Thirty-eight states and the District of Columbia have legal betting markets.

The betting interest on women’s college basketball continues to grow. BetMGM reported a 35% year-over-year increase in the amount of money bet on women’s college basketball.

Patrick Berbert, who oversees college basketball odds for Caesars Sportsbook, said the increase in popularity of the women’s game has continued after former Iowa star Caitlin Clark moved to the WNBA.

“Now, you are seeing the likes of JuJu Watkins for USC and Paige Bueckers of UConn carrying over that popular betting momentum,” Berbert told ESPN.

A 2024 study commissioned by the NCAA found that gambling-related harassment of athletes peaks during the basketball tournaments, with 73% of abusive or threatening messages that referenced betting or match-fixing allegation occurring during March Madness. Women athletes received approximately 59% more abusive messages than men, the analysis found.

The AGA, as part of its responsible gaming campaign, encourages bettors to “Keep your cool” and emphasizes that the result of a bet — win or lose — is “not an invitation to criticize players, coaches, or officials online or in-person.”