Gillian Welch and her musical partner David Rawlings wrapped up a six-month, 90-plus show tour of the U.S. and Europe with a sold-out show at Boston’s Wilbur Theater last Tuesday night. It was the second of two nights at the Wilbur, and the duo were in fine form, with not even a hint of the road weariness that can creep in after so many months on tour.

Their latest album, The Harrow & The Harvest, was released right about when the tour began, and has since garnered much critical acclaim, landing on quite a few Best of 2011 lists. They played every track from the album over the course of the evening, from the dark “Scarlet Town” to the dark “Silver Dagger” to the, uh, dark “Dark Turn of Mind.”

The pairing of the two artists so steeped in country, bluegrass, gospel and jazz brings something new to the surface, so their songs slip in and out of genres. Welch generally keeps rhythm on her acoustic guitar while Rawlings runs loops and dives around her, but there were times when it was difficult to tell who was playing lead, as the duo weaved notes in and around each other. They really stretched out on “Red Clay Halo,” at the end of the first set, and “I’ll Fly Away,” which was one of their encores.

Other highlights included the pair’s gentle harmonizing on “Down Along the Dixie Line”; their rendition of “Elvis Presley Blues,” off of Time (The Revelator); “Look at Miss Ohio,” from 2003’s Soul Journey; Welch’s impromptu soft-shoe tap dance (or maybe it was hard-shoe, since she was wearing cowboy boots) during “Six White Horses”; and Rawlings’ own tune, “I Hear Them All,” during which the duo sampled “This Land Is Your Land.”

Welch and Rawlings seemed reluctant to leave the stage on this final night of the tour, returning three times for encores. Rawlings said at one point that “the show is technically over…we’ll keep playing, because we don’t have to get up in the morning, but I just want you to know that the official part of the show is over.” And play on they did: “Tennessee,” “Revelator,” “The Way the Whole Thing Ends” – the last of these, for obvious reasons, tailor-made to be a finale. But they came out one more time to close the night with a shimmering cover of the Jefferson Airplane classic “White Rabbit.”