NEW YORK >> New York City’s population reached a record high last year of more than 8.6 million and has climbed 5.5 percent since 2010, according to a Department of City Planning analysis of new Census Bureau population estimates.

There were 8,622,698 people in the city last year, 447,565 more than were counted in the 2010 census.

City demographers said the new total was the culmination of an average annual gain not seen since the first half of the 20th century, when the city became dominant in everything from finance to culture and communications — and also had strong manufacturing and shipping sectors with thousands of jobs.

Joseph J. Salvo, chief demographer at the planning agency, said that, in effect, New York City added as many people as in all of New Rochelle, a city in Westchester County, each year from 2010 to 2017. The 2010 census put New Rochelle’s total at just over 77,000. He attributed some of the city’s jump to housing units planned before the 2010 census that were deferred in the recession and have been completed in the last few years.

“It’s a remarkable growth story,” Salvo said.

From 2010 to 2017, New York City led the rest of the state in population growth, with the Bronx emerging as the fastest-growing county in the state. The Bronx surged 6.21 percent, with 86,052 new residents.

But Brooklyn, with a population of 2,648,771, took in more people — 144,071 — to achieve the highest growth of any county in the state by absolute numbers. Its 5.75 percent jump from 2010 to 2017 was second as a percentage gain.

The population in Queens climbed 127,860, or 5.73 percent, to 2,358,582, making it second among counties in the state in terms of growth by numbers and third in percentage gains. Manhattan was fourth in the number of newcomers, with 78,854, a 4.97 percent expansion that ranked fifth in percentage terms (behind Rockland County, which grew 5.51 percent with an increase of 17,181 people).

Staten Island added a more modest 10,728 people, a 2.29 percent gain to 479,458.

The city accounted for 95 percent of the state’s population growth between 2010 and 2017. City demographers noted that the city’s share of the state’s population had edged up 1.2 percentage points, to 43.4 percent last year from 42.2 percent in 2010.

The demographers say the new figure is an indication of what the next census could find in 2020 and could have ramifications in Albany when legislative districts are redrawn after that. Many parts of upstate New York, particularly urban areas, have been in a chronic state of economic distress as the manufacturing sector has eroded.

By contrast, 45 of the state’s 62 counties lost population between 2010 and 2017. Three counties upstate — Chenango, Delaware and Hamilton — lost more than 5 percent of their population from 2010 to 2017. Another five counties lost more than 4 percent.

But Salvo is concerned that the Trump administration’s approach to immigration could hurt the city in the 2020 census. Of the 4.4 million foreign-born residents in New York state, 3.3 million live in the city, he said. If they are undercounted, he said, “New York City will be hurt relative to the rest of the state.”

“The problem with the current environment is it affects more than just the undocumented,” he said, “because undocumented immigrants are often in families with legal permanent residents, they’re in families with U.S. citizens and they’re not distinguishing each other by their legal status. What they all have in common is fear. They’re afraid for their relatives, and that might cause people not to respond to the census.”

A federal law protects the confidentiality of the census, stipulating that census responses can be used only for statistical computations by the Census Bureau. An accurate account is vital because, among other factors, it determines how much federal aid flows to local communities.

The boom in the Bronx lifted the borough’s population to 1,471,160, so the Bronx has climbed to within a few hundred people of its largest-ever total, 1,471,701 in the 1970 census.

That head count was taken seven years before “ladies and gentleman, the Bronx is burning” became a catchphrase for the borough’s slide into urban despair. Lloyd Ultan, the longtime Bronx borough historian, said “the final nail in the coffin” was the 1981 film “Fort Apache the Bronx.”

“The Bronx gained a reputation as a place with feral people living in rubble and ready to pounce on anybody passing by,” he said. “It’s easy to get a bad reputation. It’s much more difficult to recover from it, but finally, people are discovering what they should have known all along: the desirability of living in the Bronx.”

Now people in some neighborhoods of the Bronx worry that gentrification is pushing people out, even as the de Blasio administration presses for affordable housing, especially in the Jerome Avenue corridor. But there have also been chilling reminders of violence, as on the night last summer when a man fired a .38-caliber revolver into a police command post two miles from Yankee Stadium, killing an officer inside. The gunman’s aunt said he had been released from a hospital a week earlier, after a breakdown.

“We’ve always said the Bronx had the ability to bounce back, given its available land and zoning,” Salvo said.

But he added: “I’m quite biased.” He lives in the northeast Bronx.

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