The first full month of legal sports betting in Pennsylvania saw gamblers wager just over $16 million at three casinos.

Thursday’s report by Pennsylvania state regulators includes December results for sports betting at Hollywood Casino at Penn National Race Course near Hershey, Rivers Casino in Pittsburgh and SugarHouse Casino in Philadelphia.

For comparison, New Jersey’s casino and racetrack-based sports books took in $319 million worth of bets in December.

A fourth Pennsylvania casino, Parx Casino in suburban Philadelphia, opened its sports book in January.

A year-old state law allows owners of Pennsylvania’s 12 casinos to pay a $10 million fee to operate sports betting. States are increasingly legalizing sports betting after the U.S. Supreme Court cleared the way in May.