Perhaps it is time to get out and count people again.

The U.S. Census Bureau released a new set of population estimates late Tuesday for the nation's cities, and their numbers for communities in San Diego and Riverside counties that are as much as 8 percent lower than those posted in May by the state Department of Finance.

The state said Oceanside, for example, has about 180,000 residents, and the federal government says it has 170,000.

The Census Bureau reported population totals lower than the state's by 8,000 in Carlsbad, 7,000 in Escondido, 5,000 in Temecula and Vista, and 4,000 in San Marcos and Encinitas.

Carlsbad, Temecula and Murrieta are all listed as having populations less than 100,000 in the new report. But the state earlier put all three over that mark.

"The gap is largely a function of our being almost 10 years away from the last census -- Census 2010 is coming up next April," said John Weeks, a San Diego State University demographer, by e-mail. "As a result, all estimates are building on old numbers. So different assumptions about growth have a potentially wide margin of error."

What's striking about the gap, however, is that it is predominantly in the same direction, with the state coming in higher and the bureau coming in lower, said Ed Schafer, senior demographer for San Diego Association of Governments, a regional planning agency.

"That tells you that there is something wrong with somebody's estimating methodology," Schafer said. "That's why you need to do these things (the census) every 10 years. Otherwise, you start having data wars."

Local officials say they are frustrated by the conflicting numbers because a lot is riding on the data.

"There ought to be some sort of check and balance in the sharing of information," said Lake Elsinore Mayor Bob Magee. "The results are extremely important, in terms of funding for cities and their representation."

Demographers on both sides of the estimating aisle say they, too, are frustrated.

"The gap keeps getting larger as we go further into the 2000s," said Daniel Sheya, a demographic specialist with the Department of Finance in Sacramento. "We have met with the Census Bureau over the widening discrepancy. They are concerned about it as well."

But at this point, state and federal officials say they are counting on the next census to clear up the confusion.

"We'll just have to wait until the census comes out in 2010 and get a count to see which set of estimates is closer," said Greg Harper, a demographer with the U.S. Census Bureau in Washington.

Harper said the discrepancy is the result of different methods for estimating how many people are moving into and out of California.

Harper said the federal government relies on information gleaned from IRS tax returns to track that domestic migration.

"We think it gives us the best results," he said. "And it's a data set that we can get at the national level, for all of the counties in the country."

Sheya said the state leans on driver's license data.

"It's more timely," Sheya said. "There is a time lag factor with tax returns."

While time will tell who's right, some local officials and demographers put more faith in the state numbers.

"I would always believe the California Department of Finance over the Census Bureau since they are more in tune with trends in California," said Weeks, who is director of San Diego State's International Population Center.

Carlsbad Mayor Bud Lewis also said the state has a better handle on local trends.

But, in a poke at Sacramento's financial problems, Lewis added: "This is probably the only thing the state has a handle on."

Handle or not, the Census Bureau numbers do show a marked slowing of the rapid population growth that dominated the first part of the decade.

Lake Elsinore led the area, growing 5.2 percent from 48,452 residents on July 1, 2007, to reach a population of 50,952 on July 1, 2008, while Temecula grew 3.4 percent from 93,936 to 97,100, according to the bureau.

Other cities expanded much more gradually.

San Marcos grew 1.5 percent from 77,910 to 79,114 residents, and Carlsbad grew 1.5 percent from a population of 94,981 to 96,374, the census report indicated.

Encinitas grew 1.1 percent from 59,692 residents to 60,372; Escondido grew 1.1 percent from 135,624 to 137,103; and Oceanside grew 1 percent from 168,076 to 169,684.

Despite the avalanche of foreclosures, no area community declined.

"There still is some migration occurring, although not to the level of three years ago," said Bill Gayk, chief demographer for Riverside County's Center for Demographic Research. "And there's also births. If not another house is built and not another person moves into the county, we'll still grow due to natural increase."

Call staff writer Dave Downey at 760-745-6611, ext. 2623.

The widening population gap

The U.S. Census Bureau and the state Department of Finance use different methods to estimate city populations. A wide gap has emerged between their respective estimates.

Carlsbad

Federal estimate: 96,374

State estimate: 104,652

Encinitas

Federal estimate: 60,372

State estimate: 64,145

Escondido

Federal estimate: 137,103

State estimate: 144,831

Lake Elsinore

Federal estimate: 50,952

State estimate: 50,267

Murrieta

Federal estimate: 97,918

State estimate: 100,714

Oceanside

Federal estimate: 169,684

State estimate: 179,681

Poway

Federal estimate: 48,858

State estimate: 51,126

San Diego

Federal estimate: 1,279,329

State estimate: 1,353,993

San Marcos

Federal estimate: 79,114

State estimate: 83,149

Solana Beach

Federal estimate: 12,825

State estimate: 13,547

Temecula

Federal estimate: 97,100

State estimate: 102,604

Vista

Federal estimate: 91,144

State estimate: 96,089

Source: U.S. Census Bureau, California Department of Finance

*Federal estimates are based on July 1, 2008; state estimates are based on Jan. 1, 2009.