David G. Schwartz is the director of the Center for Gaming Research and a history instructor at the University of Nevada at Las Vegas.

LAS VEGAS — The gambling industry here and football have been seeing each other secretly since the 1960s. But Monday’s 31-to-1 vote by league owners to permit the Oakland Raiders to move to Las Vegas with (for now) no stipulations about sports betting is a sign that the league’s and city’s status has changed from “it’s complicated” to “in a relationship.”

The reason? Las Vegas has been sanitized a bit, and the National Football League isn’t as clean-cut as it once appeared.

The dominant destination for American casino gambling since the 1950s, Las Vegas became notable in sports gambling circles in the 1960s. Until the 1961 passage of the Wire Act, Minnesota’s Leo Hirschfeld was the nation’s best-known football oddsmaker and line setter. After that law made it illegal to transmit any information used to assist in gambling across state lines, Hirschfeld retired, paving the way for Jimmy “the Greek” Snyder, Bob Martin, Roxy Roxborough and a host of other Vegas-based handicappers who made Sin City synonymous with sports betting.

Since at the time, the NFL staunchly opposed any legalization of betting on football, anything Las Vegas was a no-go.

Why was the league so strongly against sports betting, which (as anyone who has played fantasy football or noticed the crowds at bars on autumn Sundays knows) leads to more interest in the game? Commissioner Pete Rozelle — as responsible as anyone for creating the modern NFL — opposed gambling for, essentially, public relations reasons. Protecting the integrity of the game and the purity of fans’ love for it, in the end, was part of safeguarding the league’s image.

“We firmly believe,” Rozelle testified before the federal Commission on the Review of the National Policy Toward Gambling in 1975, “that government-sponsored team-sport betting would soon create a generation of cynical fans, obsessed with point spreads … and constantly prone to suspect the motives of players and coaches alike. These persons will inevitably become skeptics rather than supporters, adversaries rather than advocates of our game.” They might boo a Super Bowl-winning team that didn’t beat the spread, or worse, suspect the underperforming team of being in the tank.

Rozelle acknowledged that he was more worried about suspicions of a fix than an actual fix, but cautioned that the endorsement of legal gambling would entitle thousands of armchair quarterbacks to seek legal or investigative relief for their teams’ poor performance.

So Rozelle remained opposed to legalizing betting on football, even though he admitted one of the ways the league searched for possible fixed games was to monitor the Las Vegas betting lines. His policy continued to guide the league long after he stepped down as commissioner in 1989.

That anti-gambling stance extended to all of Las Vegas; in 2003, the league refused to air a tourism ad for the city during the Super Bowl. The ad, sponsored by the Las Vegas Convention and Visitors Authority, showed no casino scenes and did not even mention gambling. The league, however, insisted that “Las Vegas” meant “gambling,” and citing a clause in its television contracts prohibiting gambling-related ads, quashed the spot, although not without creating plenty of free advertising for the city.

So what changed before Monday’s vote?

Las Vegas is no longer a desert oasis dominated by gambling; it’s a major metropolitan area of more than 2 million people, and even its gambling business is no longer all about gaming. The major resorts of the Strip have made more from rooms, food and shows than their casinos since 1999. Today, those resorts make just over a third of their income from gambling. More significantly, in 2016, for the first time even downtown Las Vegas’s gambling halls, always more focused on down-and-dirty gambling than the ritzy Strip, made more from non-gambling than gambling.  So because Las Vegas no longer means gambling, the city is acceptable. (Of course, $750 million in public funds for a stadium would go a long way toward making any city acceptable, but that’s another story.)

The second change is that the league — and the nation — have moved beyond what Rozelle feared in the 1970s. The impressionable public no longer needs to be shielded from cynicism and theories that blame adverse results on hidden conspiracies. In the era of alternative facts and fake news, no one’s running to the government for help because they lost a football bet. And the game itself — marred by steroids, concussions and all the collateral damage of any global business dependent on the athletic feats of a few hundred competitors — is no longer viewed as pure.

The NFL has already been more than comfortable with daily fantasy sports, which officials in several states have determined is gambling. It didn’t take long for 28 of the NFL’s 32 teams and the NFL Players Association to ink sponsorship and partnership deals with DFS companies, to the tune of $6 million to $7 million each. The NFL remains officially opposed to straight-up sports betting, but not so militantly anymore. Given the speed with which it accepted DFS money, the league has little moral high ground on the issue. Playing games in the shadow of the Strip’s resorts, even with sports books operating nearby, isn’t putting the NFL any closer to gambling on the outcomes of games than it already has been for years.

Ten years ago, Las Vegas couldn’t buy airtime during a Super Bowl. Within another 10 years, it will have hosted one. That turnabout is your proverbial “when pigs fly” scenario. The pigs are flying in Las Vegas today; pigskin will be following soon enough.

Maybe we’ve become the jaded, suspicious sharps Rozelle feared legal betting would turn us into. Maybe the league no longer cares about safeguarding the innocence of the game and is looking for a quick cash-in. Or maybe, just maybe, NFL owners finally understand that gambling has always been part of the game, and that forcing it underground was more about image than integrity.