Jeff Tweedy, of Wilco, performs at the Solid Sound Festival in the summer of 2015. Photograph by Lauren Lancaster / The New York Times / Redux

These days, Jeff Tweedy takes the stage wearing a broad-brimmed white hat. Late in Wilco’s set at the Kings Theatre on Friday evening, he took the hat off. The crowd roared: that is, it issued the nearest approximation of a roar that can issue from three thousand white New York professionals between twenty-five and fifty wearing designer eyeglasses and artisan-milled flannel shirts. Seconds elapsed. Tweedy put the hat back on his head. The crowd subsided, and he introduced the last song in the set. “It’s the first song Wilco recorded, twenty-something years ago,” he said. “I think we exhibit progress.”

The song, “I Must Be High,” sounds like the songs Wilco is recording these days: strummed electric and acoustic guitars, a sing-along chorus, a lyric that cuts two ways: “You always wanted more time / To do what you wanted to do / Now you got it”—generous and dismissive at the same time. Tweedy sang it offhandedly, as is his way, and most of the audience sang with him.

Yes, Jeff: Wilco has exhibited progress. The rock group, born of the alt-country movement, is the pride of Chicago, and the stalwart of its own custom label, dBpm (after a run with highbrow Nonesuch Records).** **Wilco is to the music called Americana what the Eagles were to country rock: the group that at once perfected the style, transcended it, and got popular enough to push their old bandmates even further to the margins. Jeff Tweedy, for his part, is the overachiever of the words-and-guitar generation that includes Ben Harper, James McMurtry, David Gray, and PJ Harvey. Curating a music-and-arts festival at Mass MOCA, producing Mavis Staples’s recent records, advising the National Poetry Foundation, making a solo record with his teen-age son on drums: the railroad man’s son from Belleville, Illinois, has come far.

Progress isn’t what the Kings Theatre show was about, though, and it’s not what Wilco is about for its audience. More than any other group of guys with guitars playing now, Wilco—currently six members, after some changes over the years—has eluded the ideas of youth and age, rise and fall, early and late, breakup and comeback, that defined rock-and-roll careers since Elvis played Vegas and the Beatles started communicating with one another through their lawyers. Wilco is about continuity; it’s music for the steady state of adulthood.

Wilco is Tweedy’s long-term relationship, after the starter marriage that was Uncle Tupelo, the band he and Jay Farrar formed in Belleville in their late teens. Often described as “alt country,” Uncle Tupelo was young men channelling old music—Depression-era country and blues—often on pre-war flattop guitars, mandolins, steel guitars, and so on. So when Tweedy turned to straightforward electric rock, after the band broke up, he seemed to get younger in the process. He founded Wilco in 1994, just when R.E.M. broke into the stadium circuit, with “Monster,” and Bruce Springsteen and U2 began making records that, in effect, sampled their old ones and called it extending the mythology. There was an authenticity gap, and Tweedy filled it. Wilco, a group of adults, making music for adults, has kept it real into midlife.

That is why the audience roared when Tweedy took off his white hat. For many musicians of a certain age—think of Elvis Costello, or The Edge—a hat covers up advancing age and a receding hairline. But Tweedy, who is forty-eight, seems notably indifferent to how he looks: uncombed, unshaven, pallid, husky in baggy jeans and a denim jacket. The hat isn’t a cover-up. It’s the outsize piece of finery that sets him apart from his audience. When he takes it off, he is one of us: a person squarely in midlife who has time to do what he wants to do—and who is doing it.

I felt that he was one of us, at any rate. I came to Wilco through their collaborations with Billy Bragg, a pair of now-classic records putting music to a stash of lyrics that Woody Guthrie left behind. Over the years, I saw them play twice: on Randall’s Island, in 1998, playing the heavy rock of “Being There,” and at the Bowery Ballroom, in 2002, where they goofed around—playing the Who’s famous set-closer, “Won’t Get Fooled Again,” as their set-closer. Along the way, hardly trying, I wound up with a stack of Wilco discs. Jeff Buckley (who drowned in 1996) was way more talented; Radiohead is bolder, brighter, better; Salif Keita and Susana Baca have changed my life; I am hopelessly devoted to PJ Harvey; and yet, at some point—after a friend sent me Wilco’s “Sky Blue Sky” as a gift, and I played it two hundred times—I realized that Wilco is the band I identify with: men my age sticking to rock music with a stiff-necked awareness that rock music’s best days are behind it, and defying that proposition record after record, night after night.

The Kings Theatre gig was all but designed to induce rock-show good vibes without the icky sense (it clings like old reefer smoke to classic rock) that maybe we’re all getting a little old for this. The prospect of Bill Frisell’s trio as the opening act made things seem more alive, too. Frisell has outfoxed the youth-and-age pattern in jazz the way Wilco has done in rock. After bold early work in effects-augmented jazz guitar, he turned to American roots music and took up a solid-body Telecaster, which is associated with country and rock and blues (Muddy Waters played one) more than with jazz. Meanwhile, he kept up collaborations with the eldest statesmen of jazz, such as his current run with the seventy-seven-year-old saxophonist Charles Lloyd. The effect is that, at sixty-five, Frisell seems a young man and a force of progress and catholicity in the jazz world, even as he re-imagines pop songs—the Beach Boys, Burt Bacharach, Marvin Gaye’s “I Heard It Through The Grapevine,” the movie themes on his current record, “When You Wish Upon a Star”—that are sixty years old.

Frisell never made it to the Kings Theatre: rising at dawn after a gig with Charles Lloyd in Quebec City, he was bumped from a flight to New York because a group of schoolchildren on a field trip had to be kept together, and he then spent the day waiting out one delay after another at the airport. It was a genre-defining moment missed. Although the bassist and drummer in Frisell’s trio played a spiky, driving opening set with the New York guitarist Jim Campilongo, Frisell’s music would have brought out the essence of Wilco’s music. Like him, they are straightforward musicians whose work isn’t rooted in just rock, jazz, or country but is rooted broadly in the era of recordings that began in the nineteen-thirties and has made the history of music since then a continuous present.

So Wilco made the point themselves. Their current record is called “Star Wars,” but the group knows not to take the gimmick too far. The show featured some glittery lighting, but the gadgetry took the form of several dozen electric guitars from the tail-fin era, which Tweedy and the guitarist Nels Cline passed on and off the stage like meat carvers swapping out knives at a Brazilian steakhouse. They played twenty songs from twenty years, and the older ones were next of kin to new ones such as “The Joke Explained,” a snappy riff, a found expression, a string of non sequiturs strung together by Tweedy to sound natural rather than clever. All of the songs were lit up by Cline, a lanky sixty-year-old who joined the band a decade ago and can play any style in the history of rock, from meaty guitar riffs copped from “Frampton Comes Alive!” to the ghostly high notes, coaxed out of a lap steel, that can make “Star Wars” sound like the music of the spheres.