The primary sound of “Polaroid Lovers” is rich and glossy, hinting at 1970s Laurel Canyon folk-pop and the commercial peak of Fleetwood Mac, who placed sparkling acoustic instruments in the foreground of driving pop-rock.

Jarosz hadn’t strategized the bold sound of the album; it grew out of her collaborations. “Daniel Tashian was actually the first person that I got together to write with when I started reaching out to different writers around town,” she said. “We just hit it off. And I think, naturally through working with him, this growth and blooming into this other sonic territory started to happen. But it was all led by the songs.”

The album was largely recorded live in the studio, over just nine days. “I never heard her play or sing a single wrong note in the entire recording of this album,” Tashian said in a video interview from his studio. “I have a feeling that that was because she really prepared. She renders excellent performances.”

“Jealous Moon” opens the album; written by Jarosz and Tashian, it’s a brisk, anthemic country-rocker about separation and regret, with an octave mandolin solo. “Here we are under a heartbreak sky/Baby I don’t know why I flew away too soon,” Jarosz sings, regretful but looking ahead.

Another song, “Runaway Train,” is an upbeat collaboration with Jon Randall that wouldn’t be out of place on mainstream country radio, savoring its similes: “You’ve got a heart like a runaway train/screaming down the mountainside.”

Jarosz recognizes an evolution in her songwriting, but not toward Nashville formulas. “Early on, writing felt a bit more like a diary entry, a bit more confessional, heart on my sleeve,” she said. “As I’ve gotten older, I’ve started to feel more like I’m a storyteller. I can still tell my story, but I would like to do it in a way that other people can find their story in it, too.”

Getting to the heart of the song “is what’s important to me,” she added. “It’s a never-ending journey for the songwriter. You never actually want to reach the finish line or to say, ‘Well, I figured it out.’ That’s never going to happen. And that’s why it’s great.”