March 12, 2023 is not just any Sunday. It’s “Selection Sunday,” the day the NCAA names the 68 teams that will play in the men’s college basketball tournament, as well as the 68-team field for the women’s tournament.

It’s a day that basketball fans, especially those who gamble, have come to view as a kind of holiday. Anyone who has witnessed March Madness knows that there is a lot of money behind those stands.

But the reach of betting and its legal growth in recent years have turned the annual event into a massive business.

When all is said and done, from office groups and betting with bookies to online gaming, NCAA Tournament time is the focus of billions of dollars in sports betting.

WalletHub estimates that there will be more than $10 billion in bets around the 2023 edition of the NCAA Tournament. More than 50% of people in the US will place online bets on the event.

Those are big numbers, and not all of them come in strictly honest methods.

About 40% of the money will be illegally wagered on the games, according to WalletHub. But that means the remaining tournament betting will be done through legal methods.

Legal participation has grown as more places have allowed legal betting on games, online and in person, in recent years.

In 2018, the Supreme Court struck down the Amateur and Professional Sports Protection Act of 1992, opening the door for sports betting in every state in the US. They rushed into the space and continue to unite.

In all, 36 states and Washington, DC, have legalized sports betting in one form or another. Nine more states are considering it.

The rules vary by state. Some do not allow betting on some state teams at the college level. Others don’t allow novelty bets for which there are known answers, such as what color headband a player will wear.

But the general trend is unmistakable: legalized sports betting is becoming a massive industry. Anyone who listens to a sports podcast can tell you about the growth of segments discussing «over/under» or «the spread.»

And unlike other aspects of American life, this trend seems to cut across the partisan divide. Look again at that map of legalized gambling with the blue and red shading of the 2020 presidential election.

Twenty of the 36 states that have legalized sports betting voted for President Joe Biden in 2020; the other 16 voted for former President Donald Trump. Another set of other states from both sides of the political spectrum are also considering making it legal. Overall, it’s a pretty even partisan split.

What can unite a nation so often divided along red and blue lines? Green. All those bets generate a lot of tax revenue for the states that legalize sports betting. The size and speed of tax revenue growth are impressive.

In the five years since the Supreme Court ruling, general state tax revenue tied to sports betting has grown from $38 million in 2018 to $126 million in 2019 to more than $1 billion in 2022, according to SportsHandle.com.

Although part of the increase is due to more states having legalized sports betting, part of the increase in tax revenue in states that have legalized the practice.

In fact, since the Supreme Court ruling, more than $2.6 billion in state tax revenue has been collected from sports betting. More than half, $1.5 billion, was last year alone.

Sports betting could be a new revenue stream for revenue-hungry states. The next few weeks will put a lot of money into state coffers.

If you want proof, consider Massachusetts. It recently legalized sports betting, but made sure digital betting — the ability to bet on your phone — went live on Friday, just in time for the NCAA Tournament.

And as online gambling has grown into something of a tax revenue machine, states have looked for other ways to charge or at least new ways to lure people into gambling.

Take the Sunday Oscars. Do you have any thoughts on «Everything everywhere, all at once» or «Tár»?

Go to Colorado, Indiana, Louisiana, Massachusetts, Michigan, or New Jersey. They’ll let you bet on who will go home with a golden statue, according to Bookies.com. Brackets are not required.