It’s the Gillian show (with flashes of Dave’s guitar wizardry)

“This has been a long time coming,” Andy Tenille said, gazing happily at the stage as Gillian Welch and David Rawlings returned for an encore at the outside stage in front of SECCA. “I’ve been trying to get them here for five years.”

Then he excused himself to go retrieve a camera so he could memorialize the accomplishment. The Aug. 25 concert at the Southeastern Center for Contemporary Art, which sold 900 tickets, was No. 16 in the Crossroads concert series curated by Tenille, but the first to be held outside. (A memorable concert by legendary avant-garde jazz artist Sun Ra took place on the lawn outside SECCA well before the inception of Crossroads in 2011.) Welch and her longtime collaborator, Rawlings, were simply too big of a draw to fit in the auditorium, which holds 300 people and has accommodated previous Crossroads concerts.

The outdoor setting, with concertgoers lounging on blankets and pool chairs on a grassy hillside whose curve mimics the contours of an amphitheater, created a festival-like feel. The portable toilets lining the driveway, food trucks assembled on a makeshift fairway and shuttle bus depositing people from an off-site parking lot added to the ambience.

As dusk descended, some of the late summer heat lifted, but the humidity lay thick, enhancing the tender tribute “Elvis Presley Blues,” inspired by the man who died for America’s sins of excess on Aug. 16, 1977. As the song — part of Welch’s 2001 masterpiece Time (The Revelator) — recounts, the singer was thinking about the day Elvis died, and how when he was much younger he put on a shirt that his mother made for a radio broadcast, “and he shook it like a chorus girl/ And he shook it like a Harlem queen/ He shook it like the midnight rambler, baby/ Like you never seen.”

The two musicians were having some difficulties fingering the strings on their instruments — Welch on her flat-top acoustic guitar, and Rawlings on his trademark 1935 Epiphone Olympic — not that anyone in the audience likely noticed.

“I now suspect it wasn’t the bug repellant,” Welch said after they finished the song. “It’s just the air. Everything’s really slick up here — except the performers.”

She explained that the frequent tune-ups were necessitated by the drastic change in temperature from the air-conditioned chill inside to the warm bath onstage.

The concert offered few surprises from an artist who has methodically built an impressive body of original songs over the past two decades that distill the haunting quality of folk, blues and old country music from the Great Depression. If the songs sounded familiar, that’s because nearly all were drawn from her five albums, spanning from Revival in 1996 to The Harrow & the Harvest in 2011. And they sounded familiar because they might be mistaken for a lost outtake recorded in the Southern Appalachians 80 years ago.

Rawlings, who also co-wrote many of the songs on those albums, played his usual role as indispensable partner, dispatching lightning-fast solos on his little Epiphone guitar that reached a culmination with him working the instrument like someone trying to shake out a bag of cornmeal. Notwithstanding Rawlings essential contributions, the albums all bear Welch’s name, along with the concert billing. Aside from the brutal attack of his soloing — a level of intensity approaching metal — Rawlings left the spotlight to Welch. And even his guitar accompaniment was more a foil than showpiece, with Welch’s soaring vocals breaking in with new verses amid the dissipating flurry of her partner’s solos.

Only near the end of the concert during a cover of the Guy Clark song “Dublin Blues” did Rawlings take a vocal lead on one of the verses, and then again during an enthusiastically received cover of the Johnny Cash and June Carter chestnut “Jackson” during the four-song encore, which displayed his distinctive yelp.

It’s not as though Rawlings doesn’t have his own music: His second album under the name Dave Rawlings Machine, Nashville Obsolete, came out last year — making it four years more recent than his Welch’s latest output. Nonetheless, the two stuck to the official Gillian Welch repertoire, with Rawlings deflecting requests for his own material.

Near the end of the first set, Rawlings kidded, “Someone was asking for a date song….”

The setup prompted the hapless audience member to clarify: “No, Dave song!”

“Oh, I thought you said ‘date song,’” Rawlings continued. “I’ve been thinking about that for the last four songs. I was going to say, ‘You’re at the wrong concert.’ I guess we’ll do the date song then. Whatever this next one is.”

And with that, they launched into Welch’s “Tennessee,” a downtempo number with spare instrumental architecture from The Harrow & the Harvest that wryly recounts the plight of a girl cast out of the circle of virtue because of an older man’s transgression, while nonetheless confessing that the encounter “left a twinkle in my eye.”

Introducing the next song as a “toe-tapper,” Welch led the duo into “Red Clay Halo” from Time (The Revelator). With lively instrumentation that approximates the gait of a T-Model Ford, the song tells of a farm girl who’s overlooked by the “city boys” at the dance because of the dirt under her nails and her collar. “And when I pass through the pearly gate/ Will my gown be gold instead?” Welch sang in the rollicking chorus. “Or just a red clay robe with red clay wings/ And a red clay halo for my head?”

Maybe that’s what makes Welch’s music sound like an artifact of a time of hardship and privation that preceded the sexual revolution — never does it sound wilder and more free than when contemplating the hereafter.