It’s official: America is bonkers over sports betting. Each time a new state passes a bill to make gambling on sports legal or changes a law to allow more competition among betting platforms, known as sportsbooks, it becomes ground zero in a battle between market leaders DraftKings and FanDuel, whose efforts to beat back rivals often resemble a game of Whac-a-Mole.

Take Illinois, whose most recent $483.5 million monthly “handle” (the total amount wagered on sports) and $42.2 million in gross revenue from sportsbook operators make it the fourth-largest sports betting market by revenue behind Pennsylvania, New Jersey and No. 1 Nevada. All told, Americans placed nearly $35 billion on sports bets in 2020.

With casinos facing ongoing closures due to the COVID-19 pandemic, Illinois Governor J.B. Pritzker has repeatedly suspended a law requiring bettors to register in person at a casino before they can place wagers online with their mobile devices. That ruling has opened the door for DraftKings and FanDuel.