The old friend shows up every night, big and brawny as ever. He’s on a Brooklyn family’s seventh-floor balcony in Windsor Terrace, and above the Portofino Ristorante in Forest Hills, and bellowing out of a truck rolling slowly up and down the empty canyons of Manhattan’s avenues, right on time to — with the crash of a cymbal — start spreadin’ the news.

It is 7 p.m., and the city is already clapping, a nightly outpouring of support for health care workers that has taken place for weeks. And many have added a soundtrack to their applause, as familiar as the skyline. It’s as brassy and over the top as ever — and yet, playing out across a cooped-up city of crowded apartments and masks and gloves, its bottomless optimism can visibly bring smiles, a short pause to The Pause.

I want to be a part of it — New York, New York.

“A lot of people stop doing what they’re doing and start cheering,” said George Leon, a manager at Portofino with a front-row seat to the nightly performance, when an upstairs neighbor plays it on loudspeakers from his apartment window. “It’s awesome.”

With the city in the grip of the coronavirus, Frank Sinatra’s “Theme from ‘New York, New York,’” its actual name, has once again stepped up as its anthem, as it did after 9/11 and as it does after Yankee games and police promotion ceremonies. It seems to have always been with us, a staple of the voice instantly recognizable all over the world since his prime in the 1940s and 1950s; but in fact, it’s a song that’s barely reached middle age.

The nightly performances are the latest stop in the unlikely journey of a song that, in more ways than one, almost didn’t get made at all.

In 1977, the director Martin Scorsese was making “New York, New York,” and he needed a title track. The songwriting team of John Kander and Fred Ebb wrote a song and brought it to a meeting with the director and the film’s stars, Robert De Niro and Liza Minnelli.

“We played our songs — Scorsese and Liza liked them a lot,” Mr. Kander told the Cleveland Plain Dealer in 2015. “We were just about to leave, and Bobby, over on the couch, waved his arm, and Scorsese said, ‘Excuse me just a minute,’ and he went over and talked to him. It was a very animated conversation in terms of arms, but we couldn’t hear what they were saying.”

The director returned “very embarrassed” and said Mr. De Niro found the title number “lightweight” and wanted them to try again, Mr. Kander said.

The two writers, whose credits included “Chicago” and “Cabaret,” were annoyed — “Some actor’s going to tell us what’s a good song and what’s not?” — but returned to Mr. Ebb’s apartment. “In about 45 minutes,” he said, “we wrote this song called ‘New York, New York’ — another one.” It fared better: “They seemed to like it a lot, Mr. Kander said. “De Niro was absolutely right.”

Ms. Minnelli sang the number on the film’s soundtrack, and the song seemed to belong to her. This would not last.

Elsewhere in the entertainment world, Mr. Sinatra, then in his early 60s, had recently emerged from an early retirement to a vastly changed cultural landscape from the ring-a-ding days of the Rat Pack. He looked around and saw not fellow crooners, but acts like Led Zeppelin and Pink Floyd, and he struggled to adapt.

“He had fought an ambivalent battle against the new music, sometimes trying to make it his own, almost always with heart-sinking results,” wrote James Kaplan in a biography, “Sinatra: The Chairman.”

“Frank was straining for relevance,” he wrote.

The singer’s wife, Barbara Sinatra, suggested he cover “New York, New York.”

“‘Naw, that’s Liza’s song,’” he replied, according to Mrs. Sinatra’s book, “Lady Blue Eyes.” But she persuaded him to play it at a 1978 concert at Radio City Music Hall, she wrote, and “the number he almost didn’t sing brought the house down.”

The Sinatra historian and radio personality Jonathan Schwartz was in attendance that night. “I suggested to him that he might want to record it,” he recalled this week. “He said something like, ‘We’ll see.’”

Mr. Sinatra’s daughter, Tina, in an interview Wednesday from her home in California, recalled another important voice in his ear. “He was reluctant to take it from Liza,” she said. “She told him, ‘It’s OK, Uncle Frank.’”

The following year, Mr. Sinatra set about making an ambitious triple-album, “Trilogy: Past Present Future.” Amid a curious collection of covers — Billy Joel’s “Just the Way You Are,” Neil Diamond’s “Song Sung Blue” — and a suite of songs involving space travel, he thought back to the familiar, comfortable fit of those vagabond shoes.

On Sept. 19, 1979, in a studio in Hollywood, he recorded the song at last, with Rob Fentress, a member of Sinatra’s large circle, among those crowded in the jubilant control room after the final take. “They were playing back ‘New York, New York,’ and Frank was sitting in the engineer’s chair, and he was just oblivious to all the noise,” Mr. Fentress recalled in Mr. Kaplan’s book. “He was just focusing on the song. And you could see how pleased he was. He wasn’t laughing; he was just smiling slightly. I’d seen that focused look before.”

The song would close his concerts for years to come, nudging aside “My Way” in that spot, and was the last one he performed in public, when he joined an array of stars in 1995 at a tribute for his 80th birthday. He died in 1998.

“I think he could thoroughly identify with the song, growing up in Hoboken and looking across the river at the skyline,” his daughter Tina said. “He wanted to be there. He wanted to be on the other side.”

Twenty-four years later, Allison Garber, 45, of Windsor Terrace, one of the countless New Yorkers who grew up with the song showing up like a proud uncle at ballgames and public gatherings, heard a friend say it was blasting nightly at 7 p.m. from an apartment in Manhattan.

“I wanted to bring that to my neighborhood,” she said. “It’s undeniable when you hear that last bit, you really have to point out at your city.”

She found herself a little uncomfortable with the A-number-one lyrics, “not at all about community,” and cast about for a replacement. From her balcony facing Prospect Park, she tried “Heroes” by David Bowie, “Wind Beneath My Wings” by Bette Midler, and others. Below, people passed by. Only one song seemed to make them stop, so she brought it back.

“Maybe ‘New York, New York,’ makes everybody feel like they’re that person?” she said. “That everyone is king of the hill, top of the heap.”