More than once, Linda Ronstadt has recounted the blunt welcome she received when she left her sleepy hometown of Tucson, Arizona for Los Angeles in 1964. “Honey, in this town, there are four sexes: women, men, homosexuals, and girl singers,” Judy Henske, a singer-songwriter and an employee at a folkie coffee shop, reportedly advised the new arrival. It would be Ronstadt’s introduction to the rest of her life.

To be a girl singer, as indicated by rock’n’roll memoirs by men and women alike, was often to be shunted aside and leered at, pitted against one’s peers, at the mercy of the guys in charge. Even Ronstadt felt the hot flush of competition when she first saw Emmylou Harris performing at Los Angeles’ Troubadour in the early 1970s. But Ronstadt realized that she could be jealous, or she could make a friend. When the pair finally met in 1973—while on tour with Gram Parsons and Neil Young, respectively—a lifetime friendship sparked from their shared love for another girl singer: Dolly Parton.

It would take another 14 years for Harris, Ronstadt, and Parton to release Trio, their first full-length album together. Their mutual admiration had blossomed when Ronstadt and Harris crossed paths with Parton in Nashville in the early 1970s, and they’d started singing together occasionally in the back half of the decade. Plans for a proper LP, however, got tangled in the contractual obligations of their escalating stardom and ever-expanding professional lives. Making Trio allowed each of them a long-overdue opportunity to assume a new identity in an industry that had long tried to pigeonhole them.

Trio opens with “The Pain of Loving You,” a song that Parton co-wrote with country singer and television presenter Porter Wagoner. Wagoner’s hit TV show had provided the charismatic young Parton with an early break in 1967, and though she’d only signed a five-year contract, she stayed on for seven. As a gracious parting gesture, she wrote “I Will Always Love You” and dedicated it to him. In 1979, Wagoner returned the favor with a $3 million breach of contract suit, claiming that his tutelage entitled him to a cut of Parton’s solo earnings. The dramatic falling-out between an established country star and his one-time protégée was big news—big enough that it was picked up in Billboard and on the United Press newswire. Harris and Ronstadt would have been aware of it all, even in their Los Angeles singer-songwriter enclave.

Meanwhile, their own career trials had only strengthened their bond. For decades, Ronstadt kept the yellow rose that Harris presented to her after an exceptionally nasty encounter with one of Neil Young’s bandmates in 1973; a few months later, she invited Harris out for an extended convalescence in California as she grieved the death of her former singing partner, Gram Parsons. Through difficult tours and indiscriminate egos, the friends extended comfort to one another. They, too, had butted up against powerful men in their industry who sought to fuck them one way or another.

“The Pain of Loving You” becomes a place where the women can relieve themselves of that burden, dissolving their individual identities along with their aches. “You just can’t stand to see me happy/Seems you hurt me all you can,” sings Harris, who’d spent much of Trio’s recording tangled in a private custody battle and found support with her singing partners. The pace of the song is gently upbeat, riding on a loose mandolin chop and a light rhythm section. In the chorus, the three come together, cresting a high that sounds almost flustered (“Never knowing what to do”) before slipping back down into a resigned sigh (“Oh, the pain of loving you”).

Trio radiates a sister-bestie energy, aided cosmically by three women who were born within 18 months of one another. Ronstadt once compared singing with Harris and Parton to trying on their voices, like “getting to wear the dress or the face or the figure of the prettiest girl on the block.” The three boasted serious vocal talent: Ronstadt landing blows with her bold and forthright soprano, Harris weaving with the strength and flexibility of willow branches, and Parton floating like a butterfly with her bright warble. Their braided voices had a special quality right away. “The sound that we made together surprised and astonished the three of us,” Harris recalled of their first time singing together, at her house in Los Angeles in 1975.

That sound shines brightest when the women maximize the spine-tingling charge of close bluegrass harmonies. George Lucas, who was dating Ronstadt at the time and directed the video for “To Know Him Is to Love Him,” offered a surprisingly astute assessment of his former beau and her friends: “It’s not just the voices. It’s the cultures behind the voices that blend, and their struggles.” Appalachian poverty, Arizona ranch life, rural restlessness, countercultural sea change, grown-woman heartbreak, and personal triumph all shade the emotional backdrops of Trio.

The fluid vocal harmonies belie the years it took to finally record them. In 1979, the women began working with Harris’ then-husband, producer Brian Ahern, on a pop-leaning record, but didn’t like the results and shelved it. The next several years seemed to evaporate in other commitments—tours, albums, films, and family life. The three nonetheless found ways to connect, recording one another’s songs and appearing in different combinations for duets. They palled around on a 1977 episode of Parton’s variety TV show, Dolly, performing the folk ballad “Bury Me Beneath the Willow,” which they’d first sung back at Harris’ house. Parton opened the episode with “Silver Threads and Golden Needles,” a tune Ronstadt had recorded for two different solo records, her 1969 debut Hand Sown … Home Grown and 1973’s Don’t Cry Now.

Though “Silver Threads and Golden Needles” didn’t make it to Trio, it was typical of the country-rock crossover that Harris and Ronstadt were pursuing on the West Coast. Harris had shifted from her role as duet partner to become a bandleader, strumming originals alongside songs by the Beatles, Merle Haggard, and the Louvin Brothers. Ronstadt’s own setlist grab bag overlapped Harris’ with selections from Bob Dylan and Hank Williams, plus Los Angeles contemporaries like Jackson Browne and her former bandmates in the Eagles. Harris made a live staple out of Parton’s “Coat of Many Colors,” recording it for 1975’s Pieces of the Sky, while Ronstadt cut “I Will Always Love You” for Prisoner in Disguise the same year.

In Parton, they spotted a talented peer, a kindred spirit, and a potential ally. They saw the generous, self-effacing humor, high-femme indulgence, and butterfly-knife business acumen that Parton would eventually parlay to become a full-blown cultural icon. Her effervescent disposition was a thrill to the more introverted Californians, whom she likewise recognized as devotees of a musical lineage that endured hard times with grit and grace. Country music was an integral part of the singers’ DNA, and each woman had developed a different relationship with the genre. The Tennessee-reared Parton had the closest bond by way of geographic proximity. In Tucson, the social traditions of Ronstadt’s music-loving family and dispatches from border-town radio stations kept young Linda up to her ears in song. Harris, meanwhile, had turned her attention to the 1960s folk revival as a teenager, following a childhood shaped by her Marine Corps father’s multiple relocations.

The singers’ nostalgia for the music of an earlier time shines through the album’s final two songs. Though both originated in the South more than a century ago, the sorrowful ballad “Rosewood Casket” bears a dulcimer sparkle, while the gospel-rooted “Farther Along” leans into its hymnal history. Trio shifts into the 20th century on the forlorn “Hobo’s Meditation,” a 1932 song by early country star Jimmie Rodgers, and the mawkish 1958 pop number “To Know Him Is to Love Him.” The tuberculosis-stricken Rodgers lived hard and died young at the dawn of commercial radio, and “Hobo’s Meditation” empathizes with the down-and-out drifter who wonders if the afterlife will improve on his earthly lot. Even Ronstadt, however, can’t keep the first-person descriptions of boxcars, cops, and brakemen from sounding almost like a caricature to modern ears. “Making Plans,” which dates to 1963, has aged better, drawing out the song’s waltzing, honky-tonk heart.

The Grand High Trio bestowed a de facto blessing on their selections, creating a mini repertoire of classics that resonated with these giants of their field. The songs abetting Trio’s nostalgia cuts become valuable endorsements of other girl singers (and songwriters) whose talents had not earned them the same celebrity. The women borrowed “My Dear Companion” from the Kentucky dulcimer player Jean Ritchie, whose expertise in folksong, Appalachian life, and her charming, many-stringed instrument had trickled down to Dylan, Joni Mitchell, and Joan Baez. “I’ve Had Enough” came from Kate McGarrigle, who, with her sister Anna, wrote songs that would be sung by both Ronstadt and Harris throughout their careers. (On Prisoner in Disguise, Ronstadt’s take on Parton’s “I Will Always Love You” follows “You Tell Me That I’m Falling Down,” an Anna McGarrigle co-write).

Parton’s original “Wildflowers” is Trio’s lustrous centerpiece, carried on shimmery swipes of autoharp and bass that plods along like a friendly neighborhood dog. Parton takes a more prominent lead here, delivering the refrain—“Wildflowers don’t care where they grow”—as warm supporting vocals from Harris and Ronstadt supply the same variegated beauty. The women trade off vocal leads throughout Trio, but the tunes feel shared more than divvied up. Though Parton typically wrote more of her own material than Ronstadt or Harris did, the group’s pluralistic approach to curation and performance gives Trio a sense of camaraderie and collaboration.

Across the album, acoustic guitars, fiddles, and strings breathe unencumbered, a credit to the uniquely attentive ear of engineer and producer George Massenburg. By the time Massenburg signed onto Trio, he’d worked with Ronstadt, Little Feat, Randy Newman, and Earth, Wind & Fire; prior to that, he’d developed groundbreaking technology for audio equalization. His technical affinities were a strong match for an ensemble of singers who wanted to capture their full, glorious union and the nuances of their individual voices in a clear mix. The session band included longtime studio collaborators Russ Kunkel and David Lindley, guest spots from Ry Cooder and Little Feat’s Bill Payne, and picked up bluegrass cred from guitarist John Starling and fiddler Mark O’Connor.

Working from this stable foundation, the women found the recording process easier, and the fruits of their labor sweeter. “The only big disagreements would be, ‘Are we going to use autoharp or dulcimer on this song?’” Harris told one interviewer with a smile. Parton fondly recalled Ronstadt’s perfectionist approach to vocal takes as “a pain in the ass sometimes,” though it strengthened her own singing. All three singers’ vocal talents had ripened by the time they were making Trio, and Ronstadt in particular was at a new personal best. She credited her enhanced powers to the technical demands of her recent stint on Broadway, where she’d starred in The Pirates of Penzance. Though Ronstadt takes a melancholy lead on “Hobo’s Meditation,” she belts a stunner with “Telling Me Lies.” Songwriter Betsy Cook penned it with Linda Thompson, who was divorced and operating free of the “Richard-and-” prefix of her songwriter ex-husband when she first released it on her solo debut in 1985. The arrangement—electrified keys, a little jazz guitar sting at the end—stands apart from the album’s country focus, but that didn’t stop the song from picking up a Grammy nomination for Best Country Song in 1988. It’s a buried treasure in Ronstadt’s vast catalog.

At times, Trio flags with its numerous slower ballads. Rolling Stone concluded its review by suggesting that the album must’ve been more fun to make than to hear, which occasionally rings true. “To Know Him Is to Love Him” is a light, sleepy number that breezes past in a sigh (and to know the song’s author, Phil Spector, is perhaps just as likely to despise him). Massenburg, the album’s producer, recalled that Nashville “loathed” the record. “I don’t think anybody liked the idea of three women singers. I don’t think anybody liked the idea of us not being in a niche,” Ronstadt reflected in a 2016 BBC documentary. “It wasn’t rock’n’roll, it wasn’t country, it wasn’t this, it wasn’t that. It was old-timey music.” In the same documentary, a former Warner Brothers executive noted that the record’s traditionalism was a poor fit for the commercial pop trends then bleeding into country radio. Regardless, Trio found its audience in the women’s overlapping musical circles, selling more than a million copies within five months of release. It’s not quite a historic compendium of essentials, but it certainly wasn’t the lead balloon that the country music machine had predicted.

It would take another dozen years to make a companion volume, Trio II, which arrived in 1999. Plans for a third were suspended permanently in 2013, when Ronstadt retired from singing after being diagnosed with a rare neurological disorder. The public face of the women’s lasting friendship remains an endearing sight to behold, as when Ronstadt made a rare public appearance to co-present with Harris at a 2019 MusiCares gala honoring Parton. The woman of the hour pulled Ronstadt into a tight, full-body squeeze, eliciting a spontaneous laugh. Good friends can be hard to find, but heartache, harmonies, and country songs make enduring adhesives. Trio is a testament to the invisible bonds that hold fast through personal, professional, and artistic growth: a love letter to the wildflowers who find one another, growing free and strong wherever they might go.