Nassau and Suffolk counties recorded slight population increases in 2009 over 2008, according to population estimates out Tuesday.

In the midst of the U.S. Census Bureau's once-a-decade count of the nation's population, the agency released its 2009 population estimates for counties and metro areas, the last to use the 2000 Census as a base for its calculations.

The bureau estimated Nassau's population on July 1, 2009, at 1,357,429, up from 1,353,151 in 2008. Suffolk's 2009 population is estimated at 1,518,475, up from 1,513,435 the year before.

The bureau estimates Long Island's population has grown 4.4 percent since the 2000 Census, when the bureau counted 2,753,913 people. The Island's 2009 estimate is 2,875,904. New York State's population is estimated at 19,541,453, up from 19,467,789 in 2008.

The 2010 Census population figures for the nation and states are to be released in December.

Long Island's 2009 numbers "look very much in line with what we've observed in our building permit data," said Seth Forman, chief planner for the Long Island Regional Planning Council. He said the permits show "some marginal growth that we've seen in the last year."

The census population estimates - based on 2000 census data and updated with records on births, deaths and migration - show Long Island's growth came largely from what they call a "natural increase" of births over deaths. The bureau's figures also show, however, the Island has seen significant numbers move away.

According to the estimates, Long Island saw a "natural increase" in population of 115,729 since 2000, but lost 156,239 people since then due to "domestic migration," that is, people who moved to other parts of the state or nation. International migrants brought an estimated 59,941 people to Long Island since 2000.

"Obviously, we're losing a lot of domestic migrants to other parts of the country," Forman said. He added the anecdotal information suggests some leave for "lower taxes, lower housing costs and less congestion."

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