Nassau County's population fell by 1% between the 2020 Census...

Nassau County's population fell by 1% between the 2020 Census and July 1, 2023, according to new federal data. Credit: Newsday/John Keating

Nassau County has lost 1% of its population since the 2020 Census, largely residents leaving Long Island, while Suffolk's population dipped considerably less, according to federal data released Thursday.

The U.S. Census Bureau's Vintage 2023 estimates, which tracked population declines between April 2020 and July 1, 2023, also shows that Brooklyn, Queens and the Bronx ranked second through fourth nationwide in total population losses during that three-plus year period, behind only Los Angeles.

The entire population of New York State, meanwhile, declined 3.1%, or by more than 631,000 people, although it dipped by only 0.5% in the final year of the study period, according to an analysis of the data by Cornell University’s Program on Applied Demographics.

In fact, only the Capital region has gained population. The nine other statewide regions, including Long Island, saw their numbers drop, the Census figures show. Long Island's population loss, however, was less than seven other regions in the state.

Similarly, while the population of the northeast portion of the country continued to decline — as compared to the South and Western parts of the U.S., which experienced increases — those figures slowed between 2022 and 2023, the data shows. 

“Domestic migration patterns are changing, and the impact on counties is especially evident,” said Lauren Bowers, chief of the Census Bureau’s Population Estimates Branch. “Areas which experienced high levels of domestic out-migration during the pandemic, such as in the Midwest and Northeast, are now seeing more counties with population growth.”

Long Island's total population fell 0.6%, or by 16,776 people since the Census, from 2,921,661 to 2,904,885, data shows. 

The population loss largely occurred in Nassau County, which lost 14,502 residents, or just over 1% of its residents, the Cornell analysis shows.

While the county saw more than 5,000 more births than deaths during the period — stemming some of the population decline — nearly 20,000 more residents moved out of Nassau than moved in, the data shows.

Suffolk County, meanwhile, lost only 0.2% of its population, or 2,724 people, since the Census, the data shows.

“These population changes ranked 23rd and 17th [highest respectively] among the 62 New York counties,” said Jan Vink, a researcher with Cornell's Program on Applied Demographic. “Queens, Kings [Brooklyn], and the Bronx ranked lowest and contributed to New York City's estimated loss of 6.2% since the 2020 Census.”

Census data shows New York City has lost 546,000 people since 2020, with the majority frontloaded during the first two years of the pandemic.

Since July 2022, the population of the five boroughs dropped by 78,000. But a report released Thursday by the City Planning Department indicates those recent numbers don't account for the more than 50,000 migrants that moved into the region during that 12-month period.

“The NYC Department of City Planning intends to work with the Census Bureau through their Challenge Program to add over 50,000 people who were missed in the most recent estimate,” the report states. “This adjustment offsets approximately two-thirds of the estimated population decrease, resulting in minimal population change between 2022 and 2023.”

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