LONG ISLAND CITY, NEW YORK — Lorraine Romano has owned her two-family house here for 42 years, raising her children and, more recently, hosting visiting grandchildren.

But Romano, a manager at a neighborhood Italian restaurant, found herself in an unusual position Tuesday: The house she had had on the market for months was suddenly besieged by buyers.

“Our broker called us and described the offers, which people made right after the Amazon news,” Romano noted as she worked phones and oversaw the kitchen at the restaurant, Manducatis, on Tuesday afternoon. “I said: ‘I’m ready. It’s time to get out.’ ”

Since word came Monday that the online giant would make this slowly gentrifying Queens neighborhood across the water from midtown Manhattan the site of one of its new headquarters, it has sparked enthusiasm from New York Mayor Bill de Blasio and New York Gov. Andrew M. Cuomo and anger from many local politicians.

“We are witness to a cynical game in which Amazon duped New York into offering unprecedented amounts of tax dollars to one of the wealthiest companies on Earth,” Michael Gianaris and James Van Bramer, Long Island City’s state senator and city council member, noted in a joint statement about the deal, which could ultimately bring as many as 25,000 high-wage jobs but comes with nearly $3 billion in government tax incentives.

But the reaction in this neighborhood of 20,000 has been more complicated. Some longtime residents, contrary to the conventional wisdom about local resistance, welcomed the opportunity to cash out or add to their consumer base.

At the other end of the spectrum, not all newcomers, who over the past decade have essentially presaged the Amazon move, are excited about the deal.

One thing everyone agrees on, though: Amazon did not start this fire.

“This neighborhood is already changed,” Romano said. “This just will make it change even more.”

If New York City is a microcosm of the country’s real estate boom of the past decade, Long Island City is a microcosm of New York.

Gentrification was promised long ago to this land of faded warehouses, factories and pockets of rough-eared one- and two-family homes. The Citicorp building — a 50-story glass office tower — opened in 1990 a half-mile east of the new Amazon site. The first luxury condominiums on the neighborhood’s waterfront opened in the late 1990s.

The area remained largely forgotten for years. Other places, including Hoboken, N.J., to the west and Williamsburg, Brooklyn, to the south, leaped above it on the upscaling curve.

It was not until the housing crisis a decade ago, when the market moved from owning to renting, that change took hold. The area is catnip to developers of luxury rentals: It sits several minutes by subway from Grand Central Terminal, contains striking views across the East River and has a smaller-town feel than many New York neighborhoods. Rents could be set high — if not quite Manhattan-high, then certainly enough to be awash in profits. Tenants could pay as much as $3,500 for a one-bedroom apartment.

Developers built high-end luxury apartment towers, many of them teasing New York City skyline views.

In fact, since 2010 Long Island City has seen the most new rental apartments of anywhere in the country, nearly double that of the next-highest neighborhood, downtown Los Angeles. Locally these buildings are known as “the high-rises” and are the vertical equivalent of living in a swanky estate.

On Tuesday, the day of Amazon’s announcement, the effects of this shift were on display, as Pilates studios, high-end bakeries and craft breweries could be seen on and near the main street of Vernon Boulevard. Even a barber shop was artisanal.

The popularity has had some unintended effects. Arthur Mull, who three years ago opened the boutique pharmacy Nature’s Prescriptions, said the initial promise has given way to the threat of corporate incursion.

“It’s been difficult. CVS just opened across the street,” he said. “Amazon is part of the same trend.” (The company’s chief executive, Jeffrey P. Bezos, owns The Washington Post.)

One woman pushing a baby stroller who lives in the high-rises but spoke on the condition of anonymity because of the issue’s sensitivity said she was not in favor of Long Island City’s newest occupant, even though she was part of the same wave that swept it in.

She was worried, she said, about what Amazon’s arrival would mean for the subway, whose aging infrastructure has already been buckling under massive ridership increases in recent years. (The 7 train that serves the area is routinely ranked as one of New York City’s best, a status that could be jeopardized with an influx of commuters.)

Schools are already struggling to stay under capacity, she said, could face greater challenges with the flood of 25,000 new employees — highlighting the core paradox of gentrification, in which the very perks that attracted new blood are also eroded by those residents’ arrival.

Stretching behind a green construction wall, the parcel of land the company would take over is a mix of private and public land that had been marked for rezoning. (The private land is owned by Plaxall, a plastics company.) Sitting on an area known as the Anable Basin, it features prime waterfront space and dazzling views of the east side of Manhattan across the river.

There was little evidence Tuesday of the changes to come. Near the planned site sat an ungainly taxi garage, a bunkerlike building housing the New York Blood Center and a smattering of drab government offices. The Queensboro Bridge loomed in the background, not as the softly lit vista seen from Manhattan in untold romantic comedies but as a cantilevered hulk of steel, as though one was viewing a duck confit from its bony underside.

Yet at the southern end of the site, both the river and the last in the chain of current high-rises were on view, hinting at the gleaming tech future Amazon promises. It is a tableaux that could stretch all the way toward the Queensbridge Houses, the largest public-housing development in the Western Hemisphere that sits about a half-mile north and is one of the region’s most blighted areas.

If cities are to be revamped for the future, some Long Island City residents said, it means accepting the changes and displacement that come with it.

“It’s time for the old to move out and new lives to come in,” said 89-year-old Vincenzo Cerbone, who has owned Manducatis restaurant for nearly a half-century and lives right near the Anable Basin.

Some other business owners were less optimistic.

Michael Dhoman, who has run the Silver Star Auto Express repair shop a few blocks from the headquarters site, said he wanted badly to compete in an Amazonian future but has given hope that he can. “My landlord has said he will raise the rent from $9,000 to $15,000 a month when my lease is up next year,” said Dhoman as he stood in his garage. “I’ve been here 12 years. I can’t afford that.”

Some described a Catch-22 created by the new corporate import from Seattle.

“More upper-middle class people means more customers,” said Mull, the pharmacist. “But it also means higher rents and the need to raise prices. And we can’t raise prices, because then everyone will buy everything on Amazon.”