"Tennessee remains in line with much of the country's other legal sports betting markets, with some positive signs," said Jessica Welman, analyst for the PlayUSA.com network, which includes PlayTenn.com. "June's revenue and volume boost shows the industry is still healthy. Not only does it increase tax receipts, but it also better positions sportsbooks as we move closer to the football season."

Bettors wagered $174 million at Tennessee's online sportsbooks in June, according to official data released Tuesday by the Tennessee Education Lottery and Sports Wagering Advisory Council. That is up 8% from $161 million in May and the first month-over-month gain since March. The pace of betting increased, too, to $5.8 million per day over the 30 days of June from $5.2 million per day in May. 

Sportsbooks also won a greater share of wagers in June, producing $18 million in gross gaming revenue, up 17% from $15.4 million in April. The month's win produced $16 million in taxable revenue, yielding $3 million in tax revenue for the Volunteer State.

Tennessee's 15.5% decline in betting volume from $206 million in March to June is outperforming much of the U.S. March brought the highest betting volume in U.S. history, with $4.6 billion in legal bets placed across the U.S. With no football or betting holiday like March Madness, combined U.S. handle fell to $3.7 billion in both April and May. That is off 19.6% from March's high, and the combined U.S. handle in June is on pace for a similar total as April and May.

A chief reason for Tennessee's boost in June, though, is the seasonal change of the sports landscape. Wagers on sports such as golf, tennis, and auto racing are primarily futures bets, which are much more volatile than spread or moneyline wagers that are more typical with major team sports.

"Golf and auto racing are less popular than football with bettors, obviously, but those sports can help sportsbooks offset the dip in interest that occurs every summer," said Nicole Russo, analyst for PlayTenn.com. "They can be critically important in helping to smooth out the natural seasonality of sports betting, and that might be especially true in an Olympics year such as this one."

The bump in revenue is good news for sportsbooks in more ways than just the profitability of a single month. June's 10.3% hold — the share of wagers that sportsbooks keep on events that are completed — marks just the second month sportsbooks have met the state's 10% mandatory hold requirement and the first time since November.

Sportsbooks' hold of 9.1% since launching in November is short of the threshold, even though it is higher than most regulated markets in the U.S. That could be a topic for the Sports Wagering Advisory Council as it considers new state regulations.

"I would be surprised if the SWAC does not strongly consider a change to the state's mandatory hold requirement," Russo said. "Since the rule's inception, it has felt like too high a threshold, and now we are seeing that borne out as the Tennessee market continues to mature."