By Michael Bennett

There are two play-ins tonight and tomorrow afternoon starts the 17-day celebration of the NCAA tournament, and:

The greatest concentration of illegal betting in this country with the exception of the Super Bowl!

Americans are expected to complete 70 million NCAA tournament brackets, risking on average $29 per bracket and contributing to the $10.4 billion that will be bet overall on March Madness, according to estimates released Monday by the American Gaming Association.

That includes popular office pools and is up 13 percent from last year’s tournament, the AGA says. Only a small fraction of the money bet on the tournament, around 3 percent, is believed to be wagered legally in the United States. The bulk of the remaining $10.1 billion is placed with offshore sports books and local bookmakers, according to the AGA, which represents the U.S. casino industry.

While gambling on the tournament grows, the NCAA remains opposed to all forms of sports betting — legal and otherwise — and believes it has the potential to undermine the integrity of the games and negatively impact the welfare of student-athletes.

NBA commissioner Adam Silver has come out in support of legalizing betting on professional sports and believes a federal framework of regulations would best protect the integrity of the games. Commissioners for Major League Baseball, the PGA and MLS also have publicly said they are open to sports betting.

“Generally, if the office pool charges a fee for entering the pool and awards prizes to the winner(s), then there is a serious question as to its legality. Some states exempt small pools from their gambling laws and regulations,” Washington, D.C.-based attorney Steven Eichorn of Ifrah Law, told ESPN.

“However, the issue of enforcement is an entirely different matter. Law enforcement are assuredly aware that NCAA tournament pools exist, but they have typically turned a blind eye towards it. As a practical matter, law enforcement tends to be more interested in enterprises that organize gambling on a commercial basis, not small interoffice pools.”

Sports betting is currently legal in only a handful of states, with Nevada the only state permitted to offer single-game wagering, the most popular form.

A record $422 million was bet on basketball last March at Nevada sportsbooks. That’s more than double the amount wagered on basketball in either January or February. The books won $21.5 million on basketball last March, making it the second-most lucrative basketball month ever.

The AGA, which has multiple Las Vegas sports betting companies as members, estimates that $295 million will be bet on the NCAA tournament at Nevada’s sportsbooks this year. By comparison, a record $138.4 million was bet on Super Bowl LI in Nevada. According to multiple Las Vegas sportsbook directors, the most common size of a bet on the NCAA tournament ranges from $20 to $50.