Long Island's 2012 population remained mostly flat over the past year, with Suffolk County showing a drop while Nassau County posted a net gain, according to U.S. Census Bureau estimates released Thursday.
The Island had a population gain of 2,341 from July 1, 2011, to July 1, 2012 -- far lower than the 10,000-plus increase the bureau estimated for the region between the same dates from 2010 to 2011.
Suffolk lost 9,463 people to other parts of the United States -- what the bureau calls domestic migration. The county saw an influx of 3,753 people through international migration, according to the estimates, but it wasn't enough to offset the domestic loss.
Suffolk's overall population, usually the engine that drives population increases for the Island, dropped by about 1,000 people: from 1,500,338 to 1,499,273 between 2011 and 2012.
Between the 2000 census and 2010 census, Suffolk's population grew 5.2 percent while Nassau's rose just 0.4 percent.
It was Nassau, however, that posted a modest gain in population most recently, rising from 1,345,827 on July 1, 2011, to 1,349,233 a year later -- a 3,400-plus gain.
Nassau had fewer domestic migration losses than Suffolk. The county lost 3,053 people who moved elsewhere in the nation, while it attracted slightly more -- 3,287 -- from other countries, according to the estimates.
Jan Vink, a researcher with Cornell University's Program on Applied Demographics, said he "would not be surprised" if Suffolk's domestic-migration number is revised next year.
"I think that's a high number for Suffolk," Vink said. Those migration estimates for the region have fluctuated widely over the last decade, he noted.
He said he views the domestic migration figure as "kind of preliminary," noting it is based in part on IRS tax filings that may be incomplete.
The Cornell program is an affiliate of the Federal-State Cooperative Program on Population Estimates, which consults with the Census Bureau.
To calculate population estimates, the bureau analyzes birth and death records as well as figures from other sources. For domestic migration, it looks at the number of federal income tax returns for those under age 65 that are filed over two years, along with Medicare information for the elderly. It matches that data against addresses and calculates a rate, because not everyone files a tax return or is on Medicare.
The bureau also uses its American Community Survey to assess international migration.
Another longtime source of regional population estimates has been the Long Island Power Authority. But spokesman Mark Gross said the utility is not putting out a survey for 2012, citing a lack of resources.
LIPA still tracks electric meter hookups. John Little, director of regulatory sales and prices, said residential meter hookups on Jan. 1, 2012, "were basically unchanged from 2011" for both Nassau and Suffolk. "We're seeing no growth in the number of residential accounts," he said.