On the morning of New Year’s Day, along the sleepy streets of the East Village in Manhattan, scarf-bundled crowds trickled into St. Mark’s Church in-the-Bowery to attend a 12-hour poetry reading that has been a spiritually cleansing downtown tradition since the 1970s. To its devotees, the gathering’s hypnotically lengthy programming of readings and avant-garde performances provides a dependably radical initiation into the new year.

Hosted by the Poetry Project, the nonprofit organization that has operated out of the historic church since the 1960s, the marathon serves as its biggest annual fund-raiser. About 150 writers, artists and dancers take their turns onstage until about midnight. Its performers have included William S. Burroughs, Gregory Corso, Yoko Ono, Amiri Baraka and Patti Smith. Years ago, the poet John Giorno might have provided participants with a bowl of LSD-spiked punch; these days, young attendees head to the church directly after partying at all-night raves.

Sunlight poured through stained-glass windows as guests settled in for the long haul ahead. Beneath the church’s paint-peeling ceiling, many sat cross-legged in nooks and corners, unpacking the blankets and dog-eared paperbacks they had brought with them. A few parents wearing beanies sat in chairs with their babies in tow, and a woman walked her terrier down a crowded aisle.

Lee Ranaldo, a co-founder of Sonic Youth, eventually took the stage with a guitar to perform “Forty Songs,” a tune based on the lyrics of the Beat poet Michael McClure. After finishing his six-minute set, Mr. Ranaldo hung out in the parish hall, where visitors nursed hangovers with coffee and catered pierogies from Veselka, a nearby Ukrainian diner, as they perused chapbooks for sale.

“When I first came to New York, this reading was one of the first things I wanted to see,” Mr. Ranaldo said. “Oddly enough, lots of New Yorkers still don’t know about it. It’s always had a fringe and marginal aspect to it. You’re getting Allen Ginsberg here, not Robert Frost.”

“I remember Jonas Mekas once brought a box to a reading,” Mr. Ranaldo added. “It contained Ginsberg’s beard clippings. It still gets weird here like that today.”

Greeting old friends and fellow poets was Eileen Myles, who has lived in a nearby rent-stabilized apartment since the 1970s, and was once the Poetry Project’s director.

“This is how I begin my New York life every year,” they said. “For me, the ball drops, and then there’s the New Year’s Day reading at the Poetry Project. This is also the place my education started as a young poet. You’d bring a beer and go to a workshop held by Ted Berrigan.”

They added: “I’m going to be reading a love poem I wrote called ‘Put My House.’ And I’m giving it to Palestine tonight.”

More than a thousand people passed through the church over the course of the day. Some lingered for just a few sets, whereas others committed themselves for hours, bringing out balls of yarn and knitting needles to while away the time. The marathon gradually took on the semblance of one epic, collective avant-garde spectacle to its own, and its lineup blurred through categories of genre and experimentation.

Jaye Bartell, theater manager for the Anthology Film Archives, strummed a folksy and mournful guitar tune. Journey Streams, a young writer who was introduced as a “nightlife historian based in Brooklyn,” recited an untitled work off an iPhone. A choir, Sing in Solidarity, marched to the chant of “Power to the workers. Power to the working class.” They wore red shirts, scarves and dresses and sang from sheet music in red folders.

“We are the choir of Democratic Socialists of America, New York City chapter,” Annie Levin, one of the singers, announced. “Please come to our concert Jan. 13 at the People’s Forum where you’ll be hearing some Appalachian labor songs.”

Luminaries of the poetry scene dominated the stage in the marathon’s second half.

Anne Waldman, who founded the event in 1974 during her directorship of the Poetry Project, read a poem while accompanied by a jazzy saxophonist. Cecilia Vicuña, the Chilean artist, recited a minimalistic political poem, “Ga Za.” Pamela Sneed, wearing a necklace with a hunk of quartz, presented a new work, “Barbie,” inspired by her distaste for Greta Gerwig’s summer movie.

“What if Barbie were taken to every skid row, homeless shelter in America and saw where unwanted people were dumped?” Ms. Sneed said. “What if her relatives were caught up in, and drowned by, a buoy on the Texas border trying to keep migrants out? What if she lost everything? To AIDS. Covid. What if her breasts were removed and she had to start a GoFundMe to cover medical costs?”

Chelsea Manning, the former intelligence analyst who conducted the largest intelligence leak in U.S. history, stood onstage in silence for several minutes. The church was now packed and sweltering, and people closed their eyes in meditation.

“I became very used to this experience that you just had, sitting there in silence,” Ms. Manning finally said, referring to her stay in solitary confinement. “Where I had nothing but myself and my thoughts. Just stone silence.”

“I think that there is a lot of power in silence,” she added. “I wanted to share a little piece of that.”

As midnight approached, the church emptied out, and about 60 people sat in darkness watching the marathon’s last leg. The critic Sarah Nicole Prickett gave a reading, as did Ty Mitchell, a writer and former gay pornography star. The pianist Conrad Tao performed an improvisation of Art Tatum’s 1950s recording, “Over the Rainbow.”

David Velasco, who was fired in October as the editor of Artforum after publishing an open letter that called for Palestinian liberation and a cease-fire, recited a personal essay about the events leading to his termination.

“That morning, I wake up to find a bird on the floor of the apartment unmoving, after being brought inside by the cat,” Mr. Velasco said. “It’s been tense all day as different people decide what to do me with me.” He continued: “A lawyer thinks I should write an email to buy myself time. A friend thinks I should prepare a statement. I’m crouched in the chimney trying to position my body between the bird and the cat when a voice inside me starts saying, ‘Do nothing.’”

The night’s final reading belonged to Kyle Dacuyan, the outgoing director of the Poetry Project, and his staff surprised him afterward offstage with champagne and a cinnamon-and-nut cake. Outside, in the old church’s cemetery, a lingering group hung out smoking cigarettes in the cold, talking poetry above the graves of the dead.