In what its members call “our scene,” I’m With Her qualifies as a supergroup. That scene has never quite named its genre; folk, bluegrass, Americana, roots music and acoustic music are all just approximations. The scene prizes acoustic instruments, but doesn’t rule out electric ones. It reaches back to the rural American string-band legacy of old-timey music and bluegrass, but doesn’t limit itself to purism and revivalism. It’s a bastion of oral tradition, passed down in backstage jam sessions and music camps. But it doesn’t disdain formal training — both Ms. O’Donovan and Ms. Jarosz attended the New England Conservatory of Music — and it’s well aware of pop, jazz and the internet. Among its encores, I’m With Her has a sweetly acidic version of Adele’s “Send My Love (to Your New Lover).”
The scene has flourished, for decades, below the radar of big commercial pop. Its largest media stronghold is public radio, where “The Prairie Home Companion” and its successor, “Live From Here” hosted by Chris Thile, have long insisted that there’s nothing antiquarian about songs driven by a banjo or mandolin. Ms. Jarosz, Ms. Watkins and Ms. O’Donovan all sit in frequently on “Live From Here”; after the WFUV set, they were texting birthday wishes to Mr. Thile.
All three members of I’m With Her have extensive catalogs of group recordings, collaborations and solo albums. Ms. Watkins, 36, was one-third of Nickel Creek, a Grammy-winning group that also included Sean Watkins (her brother) and Mr. Thile; it pushed string-band music toward new structures. Ms. O’Donovan, 35, was, among many other projects, the lead singer for a decade in the exploratory, acoustic-centered band Crooked Still.
Ms. Jarosz, 26, grew up listening to both bands. She was a 9-year-old mandolin prodigy when she met Ms. Watkins at a festival, and they stayed in touch. Ms. O’Donovan noticed Ms. Jarosz at 15. “You were this amazing young person,” Ms. O’Donovan recalled, turning to Ms. Jarosz. “You just had so much confidence and skill but you were never, like, ‘Look at me, I’m so good and I’m so young, heh heh heh.’ You always seemed like a peer.” Last year Ms. Jarosz’s fourth studio album, “Undercurrent,” won the Grammy award for best folk album.
After crossing paths for years, the members of I’m With Her were booked to share a workshop at the Telluride Bluegrass Festival in 2014, and they squeezed in some rehearsal time. Vocal harmonies came naturally, and all three women were immediately struck by the easy chemistry among them: a sense of musical problem-solving rather than dueling egos.
“It felt like a first date to me,” Ms. Watkins recalled. “I remember texting them and saying, ‘That was fun, right? I had a good time. Did you have a good time? Maybe we should do it again sometime?’ It was pretty mutual.”
Their first official show as I’m With Her was at the Celtic Connections festival in Scotland in 2015, and they toured in Europe, sharing one another’s songs and cover versions and figuring out their particular blend of voices, skills and taste. The trio had already built a fan base by the time the Hillary Clinton campaign started using “I’m With Her” as a slogan.
“We paused for a moment,” Ms. Jarosz said. “But for us, from the beginning, what the name represented is camaraderie and the spirit of this band — that we weren’t coming at it with our solo careers behind it, that it’s the band and we’re three equal parts.”
Ms. Watkins added, “And people were remembering it. How can you throw that away?”
The acoustic scene keeps its best players working constantly. I’m With Her slotted its tours between writing and recording the members’ solo albums, individual gigs as leader or guest, and bits of teaching. Ms. O’Donovan and Ms. Jarosz live in New York City; Ms. Watkins lives in Los Angeles. Late in 2017, logistics grew even more complicated when Ms. Watkins and Ms. O’Donovan each had a daughter.
They cleared schedules to write songs as a group, with stays at an Airbnb rental in Los Angeles and later at a friend’s farmhouse in Vermont, pooling ideas and constructing songs and arrangements together. When asked now about writing particular songs, no one is entirely sure who came up with which part.
Three weeks after I’m With Her had written an album’s worth of material — including just one cover song, Gillian Welch’s parable of hard traveling, “Hundred Miles” — the group went to record in England. They played together in real time, facing one another in an open room that also held their producer, Ethan Johns, and the engineers. “They’d have to be completely silent,” Ms. Jarosz said, “so there’s a heightened attention from everyone involved. To record it that way allowed us to capture the spark.”
That focused attention stayed palpable when I’m With Her was onstage. The audience was completely hushed, awaiting each fiddle line or banjo lick, each unexpected harmonic turn, each precise swell of three-part harmony. The band’s concentration wasn’t just a performance; it was an invitation to listen more closely.