Harris and Griffin have been on this kind of tour before. In 2004, they convened the Sweet Harmony Traveling Revue, also with Miller, as well as Gillian Welch and David Rawlings.
This new lineup is interesting for the performers' differences - in singing style, songwriting, and even guitar playing. Seated together amid acoustic guitars propped up on stands, they took turns performing in a round and often jumped in on one anothers' songs to provide backup vocals and light percussion.
There was no room for ego, but it was hard not to keep your eyes and ears on Harris, the majestic den mother of Americana, who is nearly 62. "Man, I've had a good time," she said, reflecting on her age. Harris, who doesn't always get the songwriting credit she deserves, performed evocative versions of her own "Red Dirt Girl" and "All I Left Behind," which she co-wrote with Kate and Anna McGarrigle.
Goaded by Griffin, who lived in Boston for 10 years, Harris even tried on her best Beantown accent, introducing the group as the Wicked Tahts (non-New England translation: the Wicked Tarts).
Griffin was in especially fine form and full of surprises. Her first solo outing was "Wade in the Water," a sneak peek at the gospel album she's making ("lapsed Catholic gospel record," as she called it). By turns angelic and raucous, she played the expected ("Rain") and the utterly strange ("Little God," a discordant song about "a creepy little man I was in business with").
Colvin was a trickier proposition. Her excellent guitar playing was percussive and skillful, but her selections sometimes steered the night into the warm, sleepy embrace of coffeehouse folk. In addition to her own compositions (unfortunately, Sunny did not come home Sunday night), she burrowed deep into elegant covers of Tom Waits ("Hold On") and Gram Parsons ("Hickory Wind").
The salute to Parsons was particularly poignant given his storied partnership with Harris in the early '70s. The ladies weren't working from any concrete set list, and Harris, who said she hasn't performed "Hickory Wind" in a long time, seemed surprised and genuinely moved by Colvin's rendition.
Harris responded with her "Boulder to Birmingham," written in the wake of Parsons's untimely death in 1973 and emotionally resonant to this day. As the women's voices soared on the chorus, it suddenly felt like, even without Miller, the Three Girls had plenty of buddies onstage.
James Reed can be reached at jreed@globe.com.
