Here's how much New Jersey sports bettors are likely to spend

(FOX News) - Gamblers in New Jersey could spend as much as $10 billion each year once the sports-betting market fully matures in the state, which legalized it after a highly contended, landmark Supreme Court ruling last month.

"The state of Nevada bets about $5 billion on sports in a year," said Joe Asher, the CEO of British bookmaker William Hill. "And my view is, once the New Jersey market is fully mature and all the operators are up and going and customers are used to it, you're probably looking at twice that."

At the Monmouth Park race track in New Jersey, swarms of people showed up at 10:30 a.m. on Thursday to place bets. New Jersey Gov. Phil Murphy was the first person to place a wager.

Asher, whose company is reaping the rewards of the new law, guessed that more states will be lining up to join New Jersey, Delaware and Nevada in legalizing sports betting. The Supreme Court decision struck down a federal law that had effectively barred states from legalizing sports betting on their own.