Clockwise from left: Celine Dion, Lady Gaga and the Backstreet Boys. (Lady Gaga: Kevin Mazur/Getty Images for Park MGM Las Vegas. Backstreet Boys: Denise Truscello/WireImage. Celine Dion: Denise Truscello/CDA Productions)

The allure of Las Vegas residencies fizzled out after the reigns of Elvis Presley and his Rat Pack predecessors. Live entertainment took a back seat to the rush of gambling, and with an influx of heritage acts in the century’s last quarter, the city gained its long-held reputation of being where musical talents fade away.

“Oh, I’ve heard that one before,” Chris Baldizan, senior vice president for entertainment booking and development at MGM Resorts, said with a laugh. Perhaps an apt way to describe the bulk of ’80s and ’90s performers, such as an aging Dean Martin, this reputation now couldn’t be further from the truth. Vegas is still where people go to win (or lose) next month’s rent, but it’s just as much where they go to see performances by superstar residents such as Celine Dion, Lady Gaga, Mariah Carey and, soon, Aerosmith, Cardi B, Drake and Janet Jackson.

In other words, the Vegas residency, once seen as music’s pearly gates, is thriving.

The city has Dion and her late husband and manager, René Angélil, to thank. John Nelson, a senior vice president of promoter Concerts West/AEG Presents, recalled what a risk it was for Dion to set up shop at Caesars Palace, given that residencies can span anywhere from weeks to years.

In the early 2000s, Vegas theaters still struggled to book contemporary artists, and Dion was straight off a No. 1 album release with “A New Day Has Come.” But the couple were fans of Cirque du Soleil, Nelson said, and Angélil had the foresight to try to apply its style of showmanship to another sort of spectacle.

Angélil somehow persuaded both Caesars and Concerts West to “join him in this risky, crazy idea for Celine to come here and do 200 shows a year,” Nelson said. “I mean, it was a ridiculous notion that many people didn’t understand. They thought it was way overblown and unsustainable.”

Such apprehension was arguably fair, given that Caesars spent $95 million building the Colosseum specifically for “A New Day . . . ” But the show went on to become Vegas’s most successful residency ever. Dion performed for audiences of 4,000, directed by Franco Dragone of Cirque du Soleil and flanked by about 50 dancers. The theater was exclusively hers until a year later, when Elton John presumably took note of her success and decided to jump on the residency bandwagon with a massive red piano.

John was the first of several big names to follow in Dion’s footsteps. “The Red Piano” ranks third among the highest-grossing residencies — below “A New Day . . .” and Dion’s ongoing production, “Celine,” and right above Britney Spears’s “Piece of Me,” a high-energy performance that, according to USA Today’s Marco della Cava, turned “a cavernous 7,000-seat amphitheater into a raging nightclub.”

“Piece of Me,” which opened at Planet Hollywood’s Zappos Theater in 2013, kicked off a new stage of Spears’s career — and of the residency model overall. After catching wind of her success, other millennium-era acts, such as Jennifer Lopez and the Backstreet Boys, came to town. Pair that with the post-recession, EDM-boosted proliferation of nightclubs, and “there was a pretty significant shift in demographic — in age, specifically,” Live Nation Las Vegas President Kurt Melien said of the city’s visitors. “We sort of strapped onto that: If the nightclubs can do it, we know the theaters can, too.”

The residency business went from boomer-filled to simply booming. Artists with younger fan bases no longer viewed Vegas as a “walk into the sunset,” Backstreet Boy Howie D. told Vulture ahead of the “Larger Than Life” show’s extension last year, because Dion and Spears had “made Vegas a happening spot where most artists want to go to.”

Money is, naturally, a huge factor. Along with the steady income — which, while less than what performers would make in large stadiums, can reportedly be about $1 million per show for stars of Gaga’s caliber — comes the ease of staying put. Entertainment companies continue to build venues for the incoming stars and team up with promoters to handle most of the marketing.

According to MGM’s Baldizan, the benefits of a residency outweigh any drawbacks.

“Listen, you’re maybe not going to make the same money, but pretty close to the money you’re making on a tour,” he said. “The net is, you’re not going to have to pay as many expenses. You’re not going to have to put everything in trucks and put people on buses and go on the road from city to city.”

Although the shows can be physically taxing — Gaga’s “Enigma,” per The Washington Post’s Chris Richards, begins with her “dangling from the ceiling on a metallic thread, her spine slightly curved like a fallen rococo angel” — residencies also eliminate travel. Gaga once cut a European tour short because of fibromyalgia pain, and Baldizan said part of the reason MGM was able to book Gaga, an artist at the top of her game, for two full years was that “she wanted to get off the road and take the wear and tear off her body.”

She may also have been drawn to the immense creative liberty Vegas grants artists. Whereas tours are often linked to album promotion, residencies can be whatever the artists want them to be — Gaga’s is Vegas’s first two-part residency, for which she’ll perform both pop and jazz. Janet Jackson, who recently announced a residency at MGM’s 5,200-seat Park Theater after Spears had to postpone hers, will use the stage to celebrate her long career and the 30-year anniversary of her album “Rhythm Nation.”

“That’s probably one of the best places right now where pop stars are playing,” Matt Galle, a senior agent representing Jackson at Paradigm Agency, said of the Park Theater. “Janet fit in well with the company that was there. . . . There’ll be a line around the block.”

After all, as Concert West’s Nelson pointed out, the overall number of Vegas’s visitors — about 42 million a year, or 800,000 a week — generally goes up each year. Residencies are a solid option for those who subscribe to the “Experience Economy” ideology, which is that some people prefer to experience things (travel, museums, etc.) rather than purchase material objects.

“That creates a lot of opportunity for headliners and production shows to draw people in, to see these spectacles that can’t tour,” Nelson said. “It’s all a progression of the business that Celine started. . . . People see these stars they dream of in such intimate theaters.”

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