Emmylou Harris and Vince Gill perform at Constitution Hall. (Paul Morigi/Getty Images for Blackbird Productions)

Folks showed up Saturday night at Constitution Hall for a concert, and a DVD taping broke out.

Fans and performers, in almost equal numbers, packed the room and stage in tribute to Emmylou Harris, the somewhat local girl who made a huge mark in the alt-country field long before anybody knew what alt-country was. Harris, who was backstage for all but several minutes of what would be a three-hour, 45-minute marathon, was born in Alabama but musically reared in this area. Tales abound about seeing her in local bars before she got discovered in the early 1970s, or even hearing her harmonize in the kitchen at Georgetown parties with Gram Parsons, the deceased cool kid usually credited with discovering her. For decades, there’s been an unofficial competition among music fans around these parts to say who heard Emmylou earliest.

Rodney Crowell played the “I knew her when . . . ” game early in the proceedings, recalling the night he walked into the now-gone Dupont Circle nightspot the Childe Harold while she was playing “You’re Still on My Mind.” Crowell, backed by an all-star house band led by ubiquities Buddy Miller on guitar and bassist Don Was, then crooned the song for the guest of honor. Chris Hillman, a member of the pioneering Flying Burrito Brothers who is often said to have been the guy who tipped Parsons off to Harris’s brilliance, came out for “Wheels.” Steve Earle boasted of catching Parsons and Harris together at a Houston show as a kid before rendering the preeminent outlaw country waltz, “Sin City.” Mavis Staples, who was beside Harris in the cast of the ultimate rock tribute show, the Band’s “The Last Waltz” from 1976, provided a little color to the otherwise all-Caucasian lineup while making a joyful noise on “Will the Circle Be Unbroken.”

Organizers had said earlier that the show would be taped for a DVD package, and there were constant reminders that the real purpose was for a reshowing rather than to entertain those in the building. A camera on a crane swooped in front of the stage whenever the director deemed it necessary. Some performers (Lucinda Williams on an otherwise wondrous “Hickory Wind,” for one) were reading the lyrics on monitors the way an unpracticed host would during a “Saturday Night Live” sketch. There were long breaks to reset the stage after every performance, to the point where late in the evening the crowd would cheer sarcastically each time the mob of gaffers and key grips took their rolls of duct tape and exited.

And there were some big pop-country names that will help move some units when this show hits the market. Martina McBride boomed the Louvin Brothers’ “When I Stop Dreaming.” Lee Ann Womack joined Earle for a “Pancho and Lefty” duet. Sheryl Crow had her version of “Two More Bottles of Wine,” enhanced by Vince Gill shredding a guitar solo. Alison Krauss showed up to render the hitting-bottom paean “Til I Can Gain Control Again” and to prove how unfair it is to everybody else in the lineup to throw her into these tribute shows with mortals. That voice is not human.

There were some relative obscurities on the bill, too: The combo of indie faves Shovels & Rope with Iron & Wine indicates the booker was a fan of the board game Clue. A cynic might say the young up-and-comers were put on the bill to lure millennials’ money. But Joey Ryan of the Milk Carton Kids lent another motive to Harris: “She wanted you to know that she knows about bands that you’ve never heard of before.” The Kids showed they belonged while recasting Harris’s “Michelangelo” as early Simon and Garfunkel would have, complete with an outro of amazingly harmonized “oh-ho-hos.” Conor Oberst, whose phrasing oozes earnestness and desperation, was given the event’s most unlikely assignment, tackling lead vocals on Harris’s “The Pearl,” while angelic Patty Griffin and Shawn Colvin were reduced to backup vocals on the hyper-serene song’s chorus. That’s sort of like a basketball coach making Shaq shoot a technical foul shot with Larry Bird on the bench. But somehow, someway, Oberst scored with the crowd.

Not that there was a shortage of geezers. Kris Kristofferson, at 78 years old, has a face as hard as anything on Mount Rushmore these days, and a voice as rough as the life he’s lived. But his rasping through the tender “Lovin’ Her Was Easier” provided the night’s most riveting moments.

Harris surfaced for the last time at the 3-hour, 40-minute mark, putting a provincial period on the proceedings while inviting the whole cast to join her on “Boulder to Birmingham,” a song written locally with her D.C. folk contemporary (and future “Afternoon Delight” author) Bill Danoff.

“I musta done something really good in a past life,” Harris said while acknowledging all the friends and admirers surrounding her, then walked offstage arm in arm with a Milk Carton Kid. Coming soon to a PBS fundraiser near you.

McKenna is a freelance writer.