PHOENIX — Owners of the NFL’s teams, convening Monday at a Phoenix resort for the annual league meeting, voted 31-1 to ratify the Raiders’ proposed relocation from Oakland to Las Vegas in a move that once would have been practically unthinkable given the league’s long-standing public opposition to sports gambling.

The Raiders will be the second major professional sports franchise to place a team in Las Vegas, the country’s epicenter of sports betting. An NHL expansion franchise, the Vegas Golden Knights, will begin play in the league’s 2017-18 season. With the Raiders set to join them, the sports-betting-related stigma of “Sin City” that once repelled professional leagues appears greatly diminished, if not extinguished.

The league has opposed efforts to legalize sports betting in other states throughout its history and is currently fighting the legalization of sports betting in New Jersey. Commissioner Roger Goodell regularly has said the league is against legalization efforts, and the NFL has cited the integrity of the sport as a major reason. Any overarching concerns regarding the placement of a team just blocks away from casinos that regularly take bets on NFL games — with over $132 million reportedly wagered on Super Bowl 50 through Nevada sports books in 2016 — appears to have taken a back seat to concerns around the Raiders’ inability to secure a new stadium in Oakland.

Owners initially seemed wary about the size of the Las Vegas market, with a population of around 600,000, roughly half the combined size of the Bay Area cities of Oakland and San Francisco. But those concerns melted away as the league contended there was no viable new-stadium alternative to keep the franchise in the Bay Area. After Oakland submitted a revised stadium-financing plan, Goodell reportedly wrote to Oakland Mayor Libby Schaaf that the parties were yet to find a solution to keep the Raiders in Oakland.

“We believe we and the Raiders worked earnestly in Oakland for over a decade to try to find that viable option in Oakland. … I know the ownership feels they went that extra mile to try to find that solution in Oakland. … Unfortunately, as you know, we didn’t get that done and we’re all disappointed,” Goodell said Monday.

It is the third franchise relocation approved by NFL owners in a little more than a year. They voted in January 2016 to ratify the Rams’ move from St. Louis to Los Angeles. The Rams played this past season in L.A., and they are to be joined there in the 2017 season by the Chargers, who announced earlier this year that they would exercise their option to move from San Diego to L.A.

The owners’ approval of the move is contingent on the Raiders getting a lease agreement and a stadium developer in Las Vegas, according to a person familiar with the details of the resolution approved Monday. The franchise is to remain in Oakland while a $1.9 billion stadium for the Raiders and UNLV’s football team is under construction. But then the Raiders are headed to Vegas for the 2019 or 2020 season.

Fans of the Oakland Raiders react to news that the team will relocate to Las Vegas once their new stadium is complete. (Ashleigh Joplin/The Washington Post)

“My father used to say that the greatness of the Raiders is in [their] future,” Raiders owner Mark Davis said. “The opportunity to build a world-class stadium in the entertainment capital of the world is one opportunity that will give us the ability to achieve that greatness.”

It is the second time that the Raiders will leave Oakland. The franchise departed following the 1981 season and played in Los Angeles from ’82 through ’94 before returning to Oakland.

“I have mixed feelings, obviously,” Davis said. “I love Oakland. I love the fans in Oakland. And I know that there’s going to be disappointment and maybe some anger. I just hope that in the future as we play in Oakland that they understand it wasn’t the players. It wasn’t the coaches that made this decision. But it was me that made it. If they have anybody to talk to about it, it should be me. And I’m going to, in the coming days, try to explain to them what went into making this difficult decision.”

Davis said he would honor any refund requests by fans in Oakland who made season ticket deposits. But he also said he believes that his father, late Raiders owner Al Davis, would have been proud of this decision.

“These are difficult decisions,” Pittsburgh Steelers President Art Rooney II said. “I think that anybody who has visited Oakland and played a game there in the last couple of years understands the stadium situation there was difficult at best. And so we needed a solution. I think that we did wait a considerable amount of time to see if a plan could be developed to keep the team in Oakland. … The future of the Raiders can be much more solid playing in a first-class stadium. And so we are happy that the Raiders are going to have a home for the long term.”

Raiders quarterback Derek Carr wrote on Twitter that he was “overwhelmed with emotion.”

Carr also wrote: “I don’t know how we should feel. I feel the pain of our fans in Oakland. I also see the joy on the faces of our new fans in Las Vegas.”

Schaaf criticized the NFL’s decision in a written statement issued Monday.

“I am disappointed that the Raiders and the NFL chose Las Vegas over Oakland when we had a fully-financed, shovel-ready stadium project that would have kept the Raiders in Oakland where they were born and raised,” she said. “I am proud that we stood firm in refusing to use public money to subsidize stadium construction and that we did not capitulate to their unreasonable and unnecessary demand that we choose between our football and baseball franchises.

“As a lifelong Oaklander, my heart aches today for the Raider Nation. These are the most committed and passionate fans any city or team could hope to have. They deserved better.”

Mark Davis set his sights on Las Vegas after the owners last year chose the Inglewood, Calif., stadium proposal of Rams owner Stan Kroenke over the Carson project proposed by Davis and the Chargers’ Dean Spanos. The L.A. option granted then to the Chargers would have passed to the Raiders if Spanos had kept his team in San Diego. But Davis didn’t wait for that possibility, pledging that he was committed to taking his franchise to Las Vegas.

Any reluctance by the league and the owners to place a franchise in the country’s gambling capital never seemed to become a significant obstacle to the move proposed by Davis. By the time Monday’s vote was taken, it had become clear that no meaningful opposition to the relocation had formed among the owners. The Miami Dolphins cast the lone dissenting vote in the 31-1 approval.

“The second announcement of a major sports franchise to locate a team in Las Vegas [along with the NHL’s Vegas Golden Knights] in just the last 12 months demonstrates how far gaming has come, from a niche industry to a $240 billion economic engine that supports 1.7 million jobs in 40 states,” the American Gaming Association said in a written statement.

“The gaming industry currently partners with professional teams around the country and we look forward to soon doing the same in Nevada. We applaud the many leaders in Las Vegas who have worked tirelessly to make the city the world’s premier tourist, convention and entertainment destination — and a market worthy of an NFL team.”

The Raiders had to scramble to reassemble the stadium-financing deal in Las Vegas when casino mogul Sheldon Adelson dropped out. But Bank of America agreed to provide the $650 million of funding that was needed after Adelson’s withdrawal. The Raiders are to provide $500 million, and there is $750 million of public financing in place.

Adelson was among the people thanked by Davis during Davis’s public remarks Monday.

The Raiders’ lease in Oakland gives them one-year team options for the 2017 and 2018 seasons. Davis said the Raiders might seek a third one-year option for the 2019 season to play in Oakland.

NFL executive Eric Grubman said the Raiders’ options for the 2019 season include playing in Oakland, playing in Vegas at UNLV or playing in another market. Grubman later suggested playing in another market would mean an existing NFL market.

“They have a unique fan base that I think is very loyal to them and will travel with them,” New England Patriots owner Robert Kraft said. “I think Las Vegas is a destination for visiting teams [and] will be very strong. … I think it’ll be a wonderful venue and a wonderful market. It’s unique — one of the only small markets I can think of that could be in that category.”

The Raiders will pay a relocation fee of an estimated $325 million to $375 million; that fee largely will be divided among the other NFL teams. Grubman declined to specify the amount of the relocation fee.

The team will be known as the Oakland Raiders as long as it plays in Oakland, Goodell said. Davis said he rejects the notion that the Raiders will be a lame-duck franchise for the remainder of their stay in Oakland. The team reached the playoffs this past season and might have been a legitimate Super Bowl threat if Carr had not been hurt before the postseason.

“Our first choice was to try and find an answer in Oakland,” Houston Texans owner Robert McNair said. “Unfortunately we were not able to do that. And the plan that the Raiders now have to be in Nevada and Las Vegas is a very sound plan. It’s one that we’ve looked at very carefully and it meets all of our standards and financial conditions. And so we’re delighted for the Raiders. We think this could lead to a more stable franchise.”

Liz Clarke contributed to this report.