"There is no avoiding a summer slowdown, but Iowa's sportsbooks are in a remarkably better position than this time last year when there was still so much uncertainty," said Jessica Welman, analyst for PlayIA.com. "Sportsbooks will continue to be innovative this summer in an effort to keep bettors engaged with the remaining NBA season, baseball, and other sports, including the Olympics. Contrast that to last summer when most were in survival mode."

Bettors placed $114.9 million in wagers at Iowa sportsbooks in May, according to official data released Thursday. That is down 2.9% from the $118.4 million in bets generated in April, and well short of the record $161.4 million in wagers in March. Betting fell to $3.7 million per day over the 31 days in May from $3.9 million over the 30 days in April.

Net operator revenue reached $6.1 million in May, down from $7.7 million in April. That resulted in $414,175 in tax revenue.

This is the second consecutive month-over-month decline for Iowa, which isn't a surprise. In April, all but one U.S. legal sports betting jurisdiction reported a month-over-month decline, including all of the nation's 10 largest markets. Of those, only Nevada (-29.1%) and Michigan (-30.5%) experienced a larger dip from March to April than Iowa's 26.7% decline.

"Iowa is more driven by college athletics than the majority of the largest markets in the U.S., so the end of college basketball season was bound to have an outsized effect," said Dustin Gouker, analyst for PlayIA.com. "But a surge by the Cubs and White Sox in May was a big help for sportsbooks. If both teams can remain relevant this summer, it should really be a boost ahead of football season."

$99.9 million in bets were made online in May, representing 87% of the state's overall handle. Retail betting accounted for the remaining $15.0 million, up from $13.8 million in April.

William Hill, which partners with six Iowa casinos, led the market again with $37.6 million in wagers, including $35.3 million in online wagers. William Hill's combined retail and online handle was down from $39.1 million in April and produced $1.1 million in net receipts.

Wild Rose, which includes DraftKings and BetRivers, was second with $33.8 million in online and retail wagering. That is down from $34.6 million in April. $33.5 million of those bets were made online. Wild Rose led the market with $1.4 million in net receipts.

Fueled by FanDuel and BetMGM, Diamond Jo took in $27.6 million in combined wagers, which included $24.3 million in online wagering. The combined bets led to a market-leading $2.5 million in net receipts.

"New operators will be pushing to launch ahead of football season, which will shake up the market a bit," Welman said. "But for the moment, it appears the market leaders in Iowa are entrenched."