"No state has come close to reaching $500 million in handle in such a short time frame after launching, and to reach that mark with just five online operators and retail casinos closed for much of January is even more impressive," said Jessica Welman, analyst for PlayIllinois.com. "Multiple factors had to come together to make that happen. The next step for the market is to get more operators online, which will help expand the pool of bettors."

Illinois online operators attracted $581.6 million in bets in January, 98.9% of which came online, according to official data released Wednesday. January's handle was up 18.3% from $491.7 million in December, fourth most among legal U.S. markets.

January's bets pushed Illinois past $2 billion in lifetime handle, but more importantly, it generated a record $49.4 million in operator revenue, up 106.8% from $23.9 million in December. The win yielded $7.2 million in taxes for the state.

January is just the opening month in a year that could bring in more than $6 billion in wagers and $450 million in operator revenue, according to PlayIllinois projections. But that assumes continued maturity, including the addition of new operators.

To that end, Illinois will get a boost with the addition of Penn National's Barstool-branded app, which is scheduled to launch on Friday.

"Seeing an impactful operator such as Barstool launch is a reminder that Illinois still has so much more room to grow," said Joe Boozell, analyst for PlayIllinois.com. "A few uncertainties could slow the market, including the potential return of in-person registration. But January's results are more evidence that 2021 will almost certainly mark a sizable leap forward for the state's sports betting market."

Basketball drew $229.7 million in wagers, 39.5% of the state's total handle. Football brought in $158.3 million bets.

With the state's ban on betting on in-state college teams, sportsbooks did miss out on the opportunity to capitalize on the college basketball success of Illinois and Loyola Chicago. But legislation is currently proposed that could remove the ban, which would allow bettors to place wagers on local teams.

"In every legal market local teams, particularly those that are playing well, are crucial in fueling bettor engagement with sportsbooks," Welman said. "Illinois isn't alone in barring betting on in-state college teams, but it does artificially suppress wagering."

DraftKings/Casino Queen led with 42% of the state market share with its $244.2 million combined handle in January, which was up from $195.4 million in December. That included $243.5 million in online bets.

"Having retail sportsbooks reopen was an important step for the state industry, even if sportsbooks weren't as busy as they would've been during an ordinary year," Boozell said. "With the retail market back in business, and the roster of online sportsbook operators growing, the coming months should offer a more trustworthy gauge of where Illinois is as a market."