If you think the census is just a once-a-decade exercise in counting the nation's population -- with facts about race and ethnicity tossed in -- think again.

The 2010 Census for New York, scheduled for release Thursday, will have far-reaching political, social and economic impacts across Long Island, government officials and experts say.

Census data affect how congressional and state legislative boundaries are drawn -- a process that can be rife with political intrigue and partisanship.

The information also drives distribution of about $400 billion in annual federal aid to states, local governments and tribes for everything from transportation to housing.

Business executives also look at the data for emerging ethnic groups and taking age and income levels into account for future housing and retail projects.

"It's used in so many ways," said Pearl Kamer, chief economist for the Long Island Association, the region's largest business group.

From a local government standpoint, the information helps planners determine where to build roads and sewer and water systems, and whether to expand or contract social and health services, said Suffolk County Executive Steve Levy.

The first data dump will provide population counts and racial/ethnic breakdowns for every community on the Island. More releases later in the year will delve into personal income, housing, education and more.

advertisement | advertise on newsday

Local experts anticipate modest Island population gains and a continuing trend toward diversity, with Hispanics and Asians driving the change. Nassau and Suffolk growth won't be "explosive, like it was between 1950 and 1960, and 1960 and 1970," said Lee Koppelman, director of Stony Brook University's Center for Regional Policy Studies.

Population figures and other information translate into funding for a range of local government programs. In 2008, Long Island received about $3 billion in federal funding, according to a Brookings Institution report.

The stakes are high enough to have Hempstead Village Mayor Wayne Hall on tenterhooks.

"We want a good count because we want the money that we deserve," he said recently.

The village doesn't get a lot of federal funding: about $1.5 million from the Community Development Block Grant mainly for streetscape and storefront redevelopment. But population and poverty numbers help officials pursue state aid and grants.

Like other communities with many immigrants and poor residents, Hempstead Village is considered hard to count. Officials were dismayed by the 2000 tally of 56,544 and lower estimates since then, citing increases in water use and trash collection.

"I can't believe that when I see the Hispanic population really growing," Hall said. "I see a lot of crowded homes."

Concerns about hard-to-count populations prompted the Hagedorn Foundation to team up with other groups to finance $335,000 in grants to 15 nonprofits for census education outreach in two dozen largely minority and immigrant communities on the Island. "There are direct consequences to an undercount for any county in this country," said Darren Sandow, Hagedorn's executive director.

advertisement | advertise on newsday

Riverhead Supervisor Sean Walter is anticipating a population increase, noting that census takers extensively interviewed residents because so many receive mail at post office boxes.

"The Census Bureau took a special interest in the East End and went door to door," he said.

New York will lose two seats in the House next year because its population hasn't grown as fast as Southwest and Western states. Several analysts said the decrease would most likely eliminate a Republican and Democratic seat, but there is disagreement on whether both would be upstate or one from Long Island.

Some experts point to the census' value in providing data that help to expose social and economic inequities. "The extent to which Long Island is still concentrating [people] by race and poverty is an important question for the region," said Lawrence Levy, executive dean of Hofstra University's National Center for Suburban Studies. "It goes beyond the Kumbaya of what's right and wrong and to our very economic existence."