The bureau now uses a formula that includes the number of building and demolition permits to determine population estimates for cities. In the past, they used federal income tax returns, Harper said.
Overall, bureau officials think the change has provided more accurate estimates, Harper said.
Kautz said the formula doesn't account for people moving into existing housing. For example, a family of four might move into a home previously occupied by one person.
Harper said Kautz is right, the formula doesn't take that into account.
There's a possibility Hagerstown's numbers could be off because of the city's large stock of existing housing, Harper said.
The change in the way population estimates are calculated makes the numbers suspect, Kautz said.
No one will really know the truth until the results of the 2000 census, Kautz said.
Even those numbers could be suspect because census bureau officials might not have enough funding to go door to door, which they last did in 1980, Kautz said. The 1990 census was based on mailed surveys and modeling, he said.
"I'm very surprised that they're saying we only have 34,633 residents," said Mayor Robert E. Bruchey II. Especially since the city has been adding housing, such as at North Gate development, he said.
According to revised population estimates, Hagerstown is now the sixth largest city in Maryland, behind Baltimore, Frederick, Rockville, Gaithersburg and Bowie.
Frederick bumped Rockville to become the second largest city with an estimated population of 46,227 residents in 1996, according to the census bureau. Rockville had been No. 2 since edging out Hagerstown in the 1970 census.
Population estimates are important for more than bragging rights.
Population helps determine how much money the city gets through the federal Community Development Block Grant program, Kautz said.
Kautz said he doubts the new estimates will drastically affect the amount of federal funds the city receives.
Capital News Service contributed to this story.