Erie County has experienced the biggest drop in population since the start of the decade of any county in New York State, new U.S. Census Bureau estimates show, though some state experts dispute those estimates.
Losses in Chautauqua and Niagara counties were not as steep, but still among the largest in the state.
Erie County's population dropped by nearly 14,000 people, to 936,318, between the 2000 census and last July, according to census estimates released Thursday. Nearly a quarter of those losses came in 2003 and 2004.
It's the same old story: More people are going out than coming in. And Erie County's natural increase -- about 3,500 more births than deaths since 2000 -- didn't help much.
But state demographers question some of the estimates and wonder if the figures might be exaggerating the region's exodus. The Census Bureau does an official head count every 10 years, but it annually estimates state, county and city populations by adjusting the latest census numbers using birth, death and migration data.
"We're finding that the methodology of the estimates that the Census Bureau is using does not seem to accurately gauge migration, particularly among counties where foreign-born and young adults are a substantial part of the population figure," said Warren A. Brown, a senior research associate at Cornell University, which contracts with the state to review census data.
The Census Bureau, for instance, uses tax return data from the Internal Revenue Service to track migration of people younger than 65. That gets tricky when analyzing movement of young adults. In some cases, state demographers have found inaccuracies in areas where there are many colleges, making the outward migration appear more pronounced, Brown said.
Prior to the 2000 census, in fact, the Census Bureau underestimated Erie County's population by about 24,000.
"I doubt that anyone would disagree that Western New York, Buffalo and Erie County are losing population, but maybe these methods are overstating that," Brown said.
State demographers are still analyzing the data. It is eventually up to each county to challenge the estimates, which in some cases are used in federal funding formulas, said Matthew Christenson, a Census Bureau demographer.
New York State population as a whole grew by 1.3 percent between 2000 and 2004, with the biggest increases coming downstate in Suffolk, Bronx and Orange counties, according to estimates.
Twenty-one of the 62 counties in the state lost population since the 2000 census, with the largest losses coming in Erie; Broome, 2,840; Chautauqua, 2,483; and Niagara, 1,786.
During that time, populations dipped by about 1 percent or less in Cattaraugus, Genesee, Orleans and Wyoming counties. Monroe County, by comparison, lost fewer than 200 people, while Onondaga County gained about 1,400.