A new report finds that legalized sports gambling could bring a $4.2 billion dollar windfall to the various professional sports leagues.

Congress is preparing to consider new rules for governing sports betting in the wake of a Supreme Court decision on the issue, according to reports.

California’s Indian tribe gambling monopolies are being threatened by legalized sports betting, which could pave the way for race tracks, card rooms, and online competition.

On May 14, the Supreme Court overturned a federal law that prohibits sports gambling, giving states the right to legalize sports betting.