Reaching a mass audience while maintaining any measure of quirky individuality is a tricky proposition in country music.

But in a genre that is depressingly dominated by indistinguishable dudes, Kacey Musgraves has cleverly carved out a career path as a queen of nonconformity.

Inclusivity is the brand of the 30-year-old songwriter from Golden, Texas, who played a sold-out show Friday night to a wildly enthusiastic audience at the Fillmore on her “Oh, What a World” tour.

That’s been the case since Same Trailer, Different Park, Musgraves’ 2013 album on which she established herself as a perceptive social observer on “Merry Go 'Round,” proudly announced her love of weed on “Blowin’ Smoke,” and invited an LGBTQ audience to the party on “Follow Your Arrow.”

But subverting clichés and letting your freak flag fly is not the surest path to mainstream country success. That goes even for an artist with such authentic credentials as Musgraves, who started writing songs at age 8 and whose fashion sense conjures up images of such old-time acts as Kitty Wells and Patsy Montana or, for Philadelphia-area TV viewers of a certain age, beloved children’s performer Sally Starr.

So rather than bang her head against the glass ceiling in hopes of getting played on bro-centric country radio, Musgraves has astutely reached out to a pop audience.

The secret of Golden Hour, her 2018 album that has garnered four Grammy nominations, including album of the year, is that it’s not a country record at all. (That’s true even though it won the Country Music Association’s album of the year.)

Instead, it has more to do with 1970s singer-songwriter stylings and disco, particularly on the winning takedown of a would-be hotshot on the hit “High Horse,” which was the feel-good closer at the end of Friday night’s refreshingly upbeat show.

Kacey Musgraves performs at the Fillmore in Philadelphia.
ELIZABETH ROBERTSON / Staff Photographer
Kacey Musgraves performs at the Fillmore in Philadelphia.

Does that mean that Musgraves is no longer a country artist? Not really. Her show is still loaded with hillbilly signifiers: Her top-notch band included a banjo and pedal steel guitarist, and she included a version of country duo Brooks and Dunn’s “Neon Moon” in the encore. (Though the young Philadelphia audience was far less familiar with that 1991 hit than Musgraves’ own songs, which were sung along to from start to finish.)

And though the singer, who was recently a judge on RuPaul’s Drag Race All Stars, toned down her cowgirl costuming — wearing sparkly tights, high heels and a knit winter cap — her hard-core fans were all in on the country kitsch, particularly those positioned in front, whom Musgraves dubbed “the Rainbow Hee Haw Brigade.”

And what makes all genre hairsplitting immaterial — and Golden Hour so successful — is the quality of Musgraves’ songwriting. She opened with “Slow Burn,” the album’s first single, which sets up a pattern that was repeated on the rest of the record, and throughout the night. The song is so understated, unhurried and shorn of unnecessary detail that it at first seems slight. That is, until its patient, sensual groove takes hold and is calming and corrective to the herky-jerky madness of modern life.

It’s a testament to Golden Hour’s strength that Musgraves performed all 13 of the album’s songs. The audience members — two of whom in the balcony got engaged during the title song to the singer and crowd’s delight — were happy to go deep with her, whether on the elegantly expressed “Happy & Sad,” movingly forthright “Mother” or charming put-down “Space Cowboy,” which was one of the few tracks that dragged over the course of the 100-minute show.

Musgraves has been typically savvy in touring with acts from beyond the country universe. In 2018, she opened an arena tour that played the Wells Fargo Center with Harry Styles, the One Direction heartthrob gone solo.

Natalie Prass opens the show for Kacey Musgraves at the Fillmore.
ELIZABETH ROBERTSON / Staff Photographer
Natalie Prass opens the show for Kacey Musgraves at the Fillmore.

Now that she’s headlining, she has indie acts opening for her. Friday, it was Natalie Prass, the songwriter from Richmond, Va., who made a move toward upbeat R&B-flavored pop on last year’s excellent The Future & the Past, and in particular the infectious single “Short Court Style.” Prass warmed up the crowd effectively with a tight, energetic set while fronting a five-piece band that included Dr. Dog’s Eric Slick, her fiance, on drums.

The headliner then later brought Prass out on stage to belt out a showstopping cover of Gloria Gaynor’s “I Will Survive.” The crowd cut loose to the gay and feminist anthem, which brought the show to a climax and thematically set up “Follow Your Arrow” and the piano ballad “Rainbow,” two celebrations of inclusivity.