NEW YORK — Broadway took its first dazzling baby steps back to normalcy on Saturday, as the 1,700-seat St. James Theatre welcomed 150 masked, coronavirus-tested and socially distanced patrons for a one-time event that featured performances by two Tony-winning stars: tap dancer Savion Glover and actor Nathan Lane.

The gathering was thrilling in its way, an incremental but mighty testament to the will to be together again in the theaters of America. Because this was Broadway, which has been shut down for almost 13 months — an intermission unparalleled in its history — the occasion of the first public performance carried profound emotional weight.

That was as true for the invited audience of workers from the Actors Fund and Broadway Cares/Equity Fights AIDS as it was for the performers. “Abject terror!” Lane said in an interview after the show, describing his state of mind as he took the bare St. James stage — where, 20 years ago almost to the day, he starred as Max Bialystock on the opening night of the smash hit “The Producers.” “The adrenaline was flowing. This was fly-by-the-seat-of-your-pants time.”

Organizers of the event made plans so they were not flying blind. The entry was the latest facet of the NY PopsUp festival, a months-long series across New York state meant to rev up culture-deprived fans and test the safety protocols that could normalize large-scale concert-, recital- and playgoing again. Over the next 10 weeks, similar pop-ups with other performers will be held in nine additional Broadway houses.

To attend Saturday’s gathering, guests lined up on West 44th Street a half-hour before the 1 p.m. show for a spot-check of credentials: photo ID, QR-coded ticket on an app, proof of full vaccination or a coronavirus PCR test from the past 72 hours. They then walked into the outer lobby of St. James, where they passed through a metal detector and had their ticket zapped and temperature taken. Only after that were they escorted by ushers to one of 150 reserved seats scattered throughout the cavernous space. The process appeared smooth.

Broadway theaters, with their tight lobbies, narrow rows and often antiquated ventilation systems, were always regarded as a final frontier for the return to pre-pandemic American life. Countries with lower coronavirus spread, such as South Korea and Australia, reopened theaters months ago. So managing and promoting the as-yet-unannounced reemergence of Broadway — heart of a commercial entertainment industry in New York estimated to bring $14 billion a year to the city — carries vast and life-altering implications.

New York state officials, through the governor’s coronavirus task force, have been testing the efficacy for months of the protocols for public gatherings. In January, a limited number of spectators were allowed back for Buffalo Bills playoff games; according to one state official involved in the monitoring effort, ticket holders — required to submit to testing before the games and be tracked afterward — were found subsequently to have lower infection rates than the general population. It was one indication, perhaps, that a motivation to attend public events reinforced a commitment to abide by safety rules.

Inside St. James, the sensation was a bit like gazing at an unfinished painting. The attendees were spread thinly, seated only in every other row, with the nearest person in your own row six or seven seats away. Expectant and masked, we looked like a surgical team waiting to observe an operation.

And then, suddenly, the electricity of galvanizing theatricality switched on, in the guise of Glover. Wearing white tap shoes and perched on a small platform surrounded by speakers, Glover — erstwhile star of Broadway’s “The Tap Dance Kid” and “Bring in ’da Noise, Bring in ’da Funk” — launched into a 20-minute tornado of tap. To accompany the display, Glover leaned into a microphone and intermittently sang snippets of show tunes, slivers of theater history that reminded you of what had gone away — and what might soon return.

“God, I hope I get it,” Glover repeated again and again, reciting the famous lyric at the top of “A Chorus Line.” It was the dancer’s own mnemonic pop-up: “Gotta Dance” from “Singin’ in the Rain,” he intoned at one point; “There’s No Business Like Show Business” from the movie of that title at another; “Memory” from “Cats” at a third. His frenzied tapping at times added syncopation to the a cappella song fragments. So compelling and revolutionary-feeling was this kicking up of heels that you could imagine it as the opening of a Broadway tap production choreographed by Glover, with contributions by others, such as Baakari Wilder and Ayodele Casel. Maybe a tap ballet orchestrated by Twyla Tharp to top it all off.

What followed in the presentation was Lane in “Playbills,” a new monologue by the gifted comic playwright and screenwriter Paul Rudnick. (Both pieces were directed by Jerry Zaks.) Lane played a musical theater addict so deprived of his show-tune fix that after a year of shutdown, he hallucinates a meetup of Hugh Jackman, Patti LuPone and Audra McDonald in his one-bedroom Manhattan apartment. (Well, actually, it’s one room and an alcove.)

The playlet is a delirious valentine to those with a level of passion for theater that defies reason — and a pledge of allegiance to the experience of seeing things live. As for plays on Zoom, Lane declared via Rudnick: “It’s like ‘Streetcar’ performed by the Brady Bunch.”

One of the paradoxes of the age of pandemic entertainment is that on Zoom, performers might see their muted, unmasked audience laughing, but not hear their reaction. In the theater, they can hear their unmuted, masked audience laughing, but not see their faces.

“You look out and it looks like hostages,” Lane said of the audience. “I could certainly feel the people were into it. It certainly felt strange and very emotional doing it.”

Glover, in a separate interview, said he got an invitational call from Scott Rudin, the Broadway and film producer who, with Jane Rosenthal, co-founder of the Tribeca Film Festival, is overseeing the pop-ups. “Of course, I immediately accepted,” he said, adding that the performance was improvised, much of it on the spot. So improvisational, in fact, that when his sound board fell over mid-performance, he asked a technician to come onstage and unplug a speaker, all the while continuing to tap.

“Up until last night, I was learning the lyrics of ‘Singular Sensation,’ ” he said, referring to “One,” the finale of “A Chorus Line.” “I was jamming to it until 2 or 3 this morning.”