In a city already locked up and hidden away behind lowered gates and darkened doors, its people now walk behind their own personal barriers. A population known for big mouths now must speak up so as to be heard by a neighbor, a cashier, the deli counterman, gesturing to the brink of pantomime to be understood.

From surgeon-quality personal protection to the home-stitched square and the bandit’s bandanna, New Yorkers pulled on a newly essential accessory and ventured into a landscape that changed yet again on Friday, as of 8 p.m., with the mandated wearing of masks in public.

The mask felt to many like the latest sweeping affront brought by something so small — it’s taken our schoolrooms, our jobs, our handshakes and hugs, and now, half of our very faces.

The new rule would be striking anywhere, but more so in New York City, where teeming crowds and if-I-can-make-it-there chutzpah are baked into the national imagination. It was as if a curtain had fallen after a grand performance, but more — eight million little curtains, actually.

“This is just the next step,” said a retired corrections officer, Stanley Woo, 63, sitting down to play chess in a park in Forest Hills, Queens, with his old friends and his new mask.

“Nobody likes it, but we’ve got to do what we’ve got to do,” said Amanda Neville, 43, inside her wine store, Tipsy, in Clinton Hill, Brooklyn.

As part of his latest measures to contain the coronavirus, which has killed more than 12,000 people in the state and infected more than 200,000, Gov. Andrew M. Cuomo rolled out the executive order this week in winding, street-level detail that could have been describing, not long ago, most any New Yorker’s average morning.

“So,” he said, “if you’re going to get on public transit, you’re going to get on a bus, you’re going to get on a subway, you’re going to stand on a subway platform, you’re going to walk in a neighborhood that is busy, you’re going to be on a sidewalk, you’re going to pass other people on a sidewalk, you’re not going to able to maintain social distancing, you must wear a mask or cloth or an attractive bandanna or a color-coordinated bandanna cloth, but you have to wear it in those situations.”

One imagines how the governor might describe the act of wearing a mask as the days stretch on: You’re going to forget to not touch it, you’re going to accidentally pull it down to speak, you’re going to hate the way it smells, you’re going to have to use a passcode to unlock your phone, you’re going to fog up your glasses. But you have to wear it in those situations.

Maryland, New Jersey and Pennsylvania are requiring that masks be worn in stores; likewise in Los Angeles and some surrounding California counties. New York’s order is the most expansive, requiring face coverings anywhere in the state where two people might come within two yards of each other, though for now, there is no fine for disobeying.

The new rules veered into uncharted territory; they generally apply to anyone age 2 and up, though in Pennsylvania, parents of children between 2 and 9 were told they “must make reasonable effort” to put, and keep, masks on them.

New Yorkers’ enthusiasm for rigid compliance landed, as one might guess, across a spectrum.

In Prospect Park in Brooklyn, couples young and old walked behind masks, while other families, keeping their social distance, kept theirs in pockets. Bicyclists sped past with faces covered, as if imagining a cloud of the coronavirus before them.

Robert Wagner, 41, a software engineer in Forest Hills, wore a mask in a park as he played with his toddler son, Vikram. “I think that such an order should have come sooner,” he said. “It was irresponsible to advise no masks and then turn around and say, ‘OK now everybody wear them.’”

In Manhattan’s Greenwich Village, Seungjoo Kim, 25, would seem to agree.

“I honestly think it’s too late,” she said. “Most people around the city are already covering their faces. The city should have done this weeks before quarantine.”

Elsewhere, the masks brought eye rolls, one of the few facial expressions still in play these days.

“Ridiculous — they’re overdoing themselves,” said a 73-year-old shopper named Esther in line outside a grocery in Brooklyn’s Fort Greene, both wearing a mask and defying the order in spirit. “I’m not scared. I’m going to die anyway.”

Once, a person wearing a mask in public stood out. But now, it’s the other way around. On Thursday, two young women studying a takeout menu in the Lower East Side’s Essex Market, chatting and maskless as if it were a different time — say, early March — drew double takes from hurried shoppers. Outside, a man smoked a cigarette — through a hole in his black mask.

“The one thing that makes me nervous are the runners that are huffing and puffing and they go right by and they’re not wearing a mask,” said Rob Corber, 62, strolling around Washington Square Park in Manhattan with his husband. “They’ve just taken up running since the lockdown. You can tell because they’re huffing and puffing.”

Many New Yorkers sought a relationship with the mask that seemed most sensible. “It’s no joke,” said R. Vincent Razor, 68, a writer in Kew Gardens, Queens, who carries two masks in his pockets when he goes out. On Friday, he pulled one off his face for good reason: “You can’t eat lunch with a mask,” he deadpanned, lifting his last sip of coffee.

In Forest Hills, the old friends managed to sit and play chess without getting too close — Mr. Woo in his mask. Of the governor’s order, he said: “I have no objection to that. It’s what you have to do.”

His friend, Paul Croce, 73, a retired court officer, refused to put one on because it made him feel, as he put it, “cooped up like pigeons.”

The mask order is statewide and was met differently in some pockets of rural New York. Donald Bowles, owner of Don and Paul’s Coffee Shoppe in the Saratoga County town of Waterford, has adopted the policy, but said the same responses to the virus don’t necessarily apply upstate.

“I feel everything Governor Cuomo does is based on what’s happening in the city,” he said between bites of an egg, sausage and cheese sandwich from his diner. “I think different areas should be treated in different ways.”

His son, John, spoke up: “Let’s see Governor Cuomo wear his mask.”

In New York, the penalties for ignoring the order are, for now, still theoretical. “If people don’t follow it, we could do a civil penalty,” Mr. Cuomo said on Wednesday. “You’re not going to go to jail for not wearing a mask.

“By the way, people will enforce it,” he added. “They’ll say to you if they’re standing next to you on the street corner, ‘Where’s your mask, buddy?’ in a nice, New York kind of way.”

Reporting was contributed by Jo Corona, Jane Gottlieb, Nate Schweber and Alex Traub.