NEW YORK — Waves of pink-clad moviegoers passed under cardboard palm trees on the frenzied first day of “Barbenheimer.”

After a feverish drumbeat propelled forward by a mushroom cloud of memes, the most anticipated day on the year’s movie calendar finally arrived as “Barbie” and “Oppenheimer” – two movie opposites brought together by cross-marketing fate – landed in theaters.

“I think it’s the contrast,” said Lucy Ruiz, 17, as she and a friend made their way into the first showing of “Barbie” on Thursday at the Alamo Drafthouse in Yonkers, New York. “If you want to do both in the same day, it’s like two sides of the same coin.”

For Ruiz, the second half of her “Barbenheimer” would have to wait. “Maybe next week,” she said of seeing “Oppenheimer.”

But many are flocking to see both on opening weekend. The National Association of Theater Owners says some 200,000 moviegoers in North America have booked same-day tickets to each movie. The movie of the summer has turned out to be not “Indiana Jones” or “The Flash,” but a double feature.

“I don’t think I’ve seen anything like this,” says Michael O’Leary, president of the theater association, who compared the phenomenon to a sold-out Taylor Swift concert tour. “But while that’s an amazing special event that captures the cultural attention, it’s not accessible to everybody the way these two movies are. This is a phenomenon open to everyone, regardless of where they live.”

As of Friday, it was already clear “Barbenheimer” had morphed into the movie event of the year. The collision of Greta Gerwig’s bright satire of the Mattel doll and Christopher Nolan’s three-hour opus on J. Robert Oppenheimer, the so-called father of the atomic bomb, wasn’t cannibalizing ticket sales for either but fueling excitement for the most jarring and color-clashing of movie weekends.

Studios forecasts had hovered around an $80 million opening weekend for “Barbie” and about $40 million for “Oppenheimer.” But it’s likely that both will greatly exceed those totals and maybe even – especially in the case of “Barbie” – double them.

Warner Bros. said Friday that “Barbie” took in $22.5 million in Thursday previews, the best such tally of the year and a clear sign that the film will easily sail past $100 million for the weekend. Universal Pictures’ “Oppenheimer” notched $10.5 million in preshow ticket sales, a likewise strong start.

“Barbenheimer” is poised to be not just a viral trend but a box-office behemoth. For a movie industry that still hasn’t entirely recovered its pre-pandemic footing, it’s a much-needed jolt of moviegoing joy in a summer season where many of the top releases have fallen shy of expectations. Overall sales for the year are running about 20% below the box-office pace of 2019.

As much as the “Barbenheimer” fanfare has been driven by internet fascination, it’s in many ways an old-school movie weekend. Both movies are roundly acclaimed, original works by two of the best filmmakers working today. “Oppenheimer” has been hailed as a masterpiece; in my review, I called it “a kinetic thing of dark, imposing beauty.” The Associated Press’ Jocelyn Noveck called “Barbie” “brash, clever, idea-packed (if ultimately TOO packed) and most of all eye-popping lovely.”

For some moviegoers, “Barbenheimer” is their first blush with the once common practice of catching a double feature. Jack Robinson, 17, had tickets to see both movies with friends Saturday. He planned to don a suit for “Oppenheimer” before changing into pink for “Barbie.”

“I used to go to the movies a lot with my family and friends before corona happened. I’m very excited,” said Robinson. “It’ll be interesting to not leave the movie theater. Usually, it’s like bathroom and go home.”

In recent years, theater owners have often bemoaned not having enough films in the marketplace as streaming made inroads and studios increasingly concentrated their release schedules on fewer but bigger films. But “Barbenheimer” points to the possible reward when a varied group of films collectively rise the box-office tide.

“Barbenheimer” may have momentarily eclipsed last week’s top film, “Mission: Impossible – Dead Reckoning Part One” – which, despite Tom Cruise’s lobbying, is losing IMAX screens to “Oppenheimer” this weekend. But having three big movies in close proximity to one other, O’Leary said, “is a good problem to have.”

“It’s certainly preferable to the alternative,” said O’Leary.

Parrot Analytics found that global demand for the casts of each film – all of whom have been publicly enthusiastic about seeing their rival movie – grew at virtually the same rate between late April and mid-July. The audience demographics are almost opposite one another. “Barbie” is appealing to a largely female and younger audience, while “Oppenheimer” is most popular with males and those over the age of 30, Parrot found.

Yet in a much-divided America, “Barbenheimer” has been the great pop-culture unifier of 2023. There is harmony in contrast.

“I’m doing ‘Barbie’ first and then ‘Oppenheimer’ because I know ‘Oppenheimer’ is going to be something I have to digest,” says Jill Kupnick of Brooklyn.

Movie theaters are catering to the “Barbenheimer” phenomenon with double feature tickets and plenty of “Barbie”-themed promotions of candy and cocktails. But most are programming their own “Barbenheimer” days. Freelance writer Kelsey Weekman called it “the closest we’ve come to having school spirit week as adults.”

“I have a friend who has outfits picked out and knows how she’s styling her hair,” Krupnick says. “There’s a level of play involved that you rarely see in more mainstream cinema. It’s more common with Marvel movies or in the fantasy genre than something like this.”

“Barbie” and “Oppenheimer” have melded together so much that it’s become possible –— despite their vast differences — to confuse one for the other. At the Yonkers Alamo Drafthouse, a sharply dressed man wearing a pink shirt beneath a blazer inquired about showtimes for “Oppenheimer.”

A clerk courteously answered and then, noticing the man’s attire, asked, “Did you want times for ‘Barbie,’ too?”