‘Mean Girls’ is an adaptation of an adaptation. It’s one of many.

Adapting films and musicals back and forth is increasingly popular, according to a Washington Post analysis, as producers turn to proven successes with a built-in fanbase that can grow in a different medium.

The first to complete the cycle was 1957’s “Silk Stockings,” based on a musical adapted from the 1939 romantic comedy “Ninotchka.” But the majority of these musical movies have come out since 2000, and many in just the past few years.

For Hollywood studios, adapting a movie to stage is relatively inexpensive compared to movie production. And a theatrical success is likely to become a musical film, which can reach new, global audiences.

For fans and creators there’s a “sort of perpetual mobility, it keeps everything rolling,” said Olaf Jubin, an associate lecturer at Goldsmiths University of London.

Tina Fey wrote the original “Mean Girls,” produced the musical and wrote and produced the new film, gaining new audiences and recognition with each step.

So many people know and love the original “The Color Purple” film, said academic and musical theater commenter Trevor Jones. “And the fact that Oprah produced the musical and was in the movie, all of that connection comes down to sales.”

The movie-to-musical-to-movie production line is a minor note in the larger Hollywood and Broadway relationship that puts musicals on screen and movies on the stage.

In the early years of Hollywood, studios turned to Broadway for storylines. More recently, the trend has turned the other way as Broadway takes advantage of putting known works — often cult-classics like “Legally Blonde” and “Groundhog Day” — on the stage.

Over a quarter of shows playing on Broadway right now are based on films, and dozens of adaptations have toured or played regional theaters over the past few decades.

The earliest films often bore little resemblance to the musicals in which they were based. Copyright law at the time meant profits from a close retelling largely bypassed Hollywood studios going straight to the original writers.

Without cast recordings or longer running shows, audiences rarely knew that what they saw on screen didn’t match the stage.

MGM’s 1955 “Guys and Dolls” cut songs from the 1950 stage show like “A Bushel and a Peck” and “I’ve Never Been in Love Before,” while adding new ones in their place, like “Pet Me, Poppa” and “A Woman in Love.”

“Then what happened was musicals, which used to last like a few months and still make a profit, now started having longer runs,” said Geoffrey Block, author and emeritus professor at the University of Puget Sound.

Over time, longer running Broadway shows, like “Phantom of the Opera,” gained fanbases and larger recognition during its 35-year run. That put pressure on films to more closely match the original production, even going as far as releasing live recordings for popular shows like “Hamilton” and “Waitress.”

But authenticity is balanced with finding a broader audience. Trailers for “Mean Girls” lacked what made the musical: singing. This sort of omission is not that rare. The first official trailer for “Wonka” (2023) also seemed to hide that the movie had songs in it. The reason for this, according to reporting from Deadline, was that “test-audience focus groups generally hate musicals.”

“This is nothing new. Twenty years ago, I saw the first trailer for ‘Chicago’ and I thought … You know, where is the singing?” Jubin said.

At the same time, musicals were increasingly sourced from films. Films come with a built-in audience, which helps to fill seats, and already have a story arc to build music from and well-known visual aesthetics.

The musicals, which typically are produced in part by the film company, often end up looking to similar to the movie.

In “Back to the Future: The Musical” — with songs including “It Works” and “Back in Time” — there’s a nearly identical time-traveling DeLorean. “The famous lines are there, but also Doc and Marty McFly look exactly like the people in the movies,” Jubin said.

While “Back to the Future: The Musical” isn’t yet slated for a Hollywood adaptation, there are plenty of other adaptations in the works. A movie version of “Wicked” will premiere later this year. In the next month, musical versions of “The Notebook” and “Water for Elephants” start previews. Over 40 more are in the works, including “13 Going on 30,” “SMASH” and “La La Land.”

The Washington Post created a data set of musical and movie adaptations from the Internet Broadway Database, Internet Movie Database and Playbill, among other sources, including theater websites.

Adaptations cover a broad category including films and musicals based in part or loosely on each other, musicals based on documentaries, and spoofs of an original movie. The data set includes English-language musicals performed at workshops, regional theaters, tours, West End or on Broadway. Films included in the data set consist of English-language films produced by a major film studio and live recordings of musicals released as films.

Hanna Zakharenko grew up listening to musicals and often sang car karaoke to “Memory” from Cats, but her favorite show to this day is “Into The Woods.” Editing by Kate Rabinowitz, who grew up seeing Broadway shows that are lost to memory, and Reuben Fischer-Baum, whose favorite musical adaptation is “Stop the Planet of the Apes. I Want to Get Off!” (Although his favorite musical number is “Rose’s Turn.”)