Upstate New York is staggering from an accelerating exodus of young adults, new census results show. The migration is turning many communities grayer, threatening the long-term viability of ailing cities and raising concerns about the state's future tax base.

From 1990 to 2004, the number of 25-to-34-year-old residents in the 52 counties north of Rockland and Putnam declined by more than 25 percent. In 13 counties that include cities like Buffalo, Syracuse and Binghamton, the population of young adults fell by more than 30 percent. In Tioga County, part of Appalachia in New York's Southern Tier, 42 percent fewer young adults were counted in 2004 than in 1990.

"Make no mistake: this is not business as usual," Robert G. Wilmers, the chairman of M & T Bank in Buffalo, told his shareholders this spring. "The magnitude and duration of population loss among the young is unprecedented in our history. There has never been a previous 10-year period in the history of the upstate region when there has been any decline in this most vital portion of our population."

In New York City and the five suburban counties in New York State, the number of people ages 18 to 44 increased by 1.5 percent in the 1990's. Upstate, it declined by 10 percent.