What could be the most-heavily-bet NFL season ever kicks off this week with legal sportsbooks operating in approximately half the states in the United States.

According to survey results released Tuesday by the American Gaming Association, 45.2 million Americans are expected to bet on the NFL this season, a 36% increase compared to last season's survey. The uptick is attributed primarily to the expanding regulated sports betting market.

At the start of the 2020 NFL season, 18 states and the District of Columbia offered legal sports betting. A year later, 23 states and the District of Columbia have already active betting markets, with Arizona, South Dakota and Washington poised to launch ahead of Thursday's NFL opener between the Dallas Cowboys and Tampa Bay Buccaneers. Thirty-two states, overall, have passed sports betting legislation.

In this new landscape, the NFL has partnered with seven sportsbook operators in the U.S. and for the first time will allow sports betting commercials to air during game broadcasts. The NFL, in an attempt to avoid oversaturation, is limiting sports betting commercials to six: one pregame, one per quarter and one at halftime.

"We looked at a lot of different approaches and thought that the spacing [of the sports betting commercials] made sense," Chris Halpin, chief strategy and growth officer at the NFL, told ESPN. "Our partners, media partners agreed. We viewed it as a balanced way to introduce sports betting advertising into our national broadcasts."

The NFL, however, is not ready for overt discussion of point spreads and odds during national broadcasts and has asked media partners to refrain from such topics. Betting will be more visible in pregame coverage, shoulder programing and scrolling tickers, though, including on NFL Network.

The American Gaming Association survey found that an estimated 37% of NFL fans are planning to wager on the league this season, including 47% of responders who identified as "avid" NFL fans. Sixty-three percent of NFL fans who responded to survey said sportsbooks at stadiums add value to the in-person experience. The NFL allows stadiums in states with legal sports betting markets to have betting lounges with mobile betting options, but accepting in-person bets at venues remains prohibited.

"Fans are the heartbeat of professional sports, and leagues like the NFL are realizing the full potential of sports betting to drive fan engagement," Bill Miller, president of the American Gaming Association (AGA), said in the release announcing the survey results.

Online betting has become by far the preferred method in the U.S. An estimated 19.5 million adults will place an NFL bet online this season, up 73% from 2020, according to the AGA's national survey of 2,200 American adults. The survey found that an estimated 14.6 million adults will participate in a paid fantasy content or other type of pool competition this year, a 69% year-over-year increase.

Nearly $27 billion has been bet with U.S. sportsbooks in the first seven months of 2021, according to the AGA.