In 2009 the county's estimated population was 91,291, a 2.6% drop from the decennial count in 2000 (93,765), but still a 2.4% percent increase from the official count in 1990.

As was the case in 1990, the adjusted numbers for the 2000 census were produced by a survey, in this case one involving 314,000 households, conducted by the bureau after the traditional decennial count was completed.

The Census Bureau's much-awaited decennial count showed a 13.2 percent increase during the 1990's.

In the years between decennial counts, the Census Bureau resorts to what Mr. Campbell described as a "computerized cohort component projection model" to estimate population.

The federal government has spent billions of dollars trying to produce an accurate count as response rates have continued to decline with each decennial count.

Every year between its decennial counts of the nation, the Census Bureau estimates populations of America's 3,141 counties.

In a reflection of the growing importance of the disputes over census methodology, the bureau's Commerce Department overseers, who have traditionally remained aloof from statistical details, have said they will decide whether to adjust the figures from the decennial count.

In 1990 it cost the bureau $2.6 billion for its decennial count.

Noting that the country had never before used statistical formulas to adjust the decennial count, he added, "We cannot proceed on unstable ground in such an important matter of public policy."

Since the first census in 1790, the decennial count has been the basis for the United States representative form of government.