Utah's population has topped 2.5 million for the first time, and the state's growth is being driven largely by a record number of people moving into the state, according to the Utah Population Estimates Committee.

Utah gained an estimated 40,647 people through migration between July 1, 2004, and July 1, 2005. That's more than double the net in-migration — the difference between people moving in and out of the state — for the previous year.

It's also the largest net in-migration in the state's history and a sign of a strong economy, said Pam Perlich, senior research economist at the University of Utah and a member of UPEC.

"It's a lot bigger than we expected. . . . It's really being driven by the economy," Perlich said. "We can say the good times are back here in Utah after some very lean years."

Utah's total population grew by an estimated 3.2 percent in one year, or 78,159 people — enough to fill a city the size of Ogden.

While the growth rate isn't record-setting, it is the largest since 1992, according to the population estimates.

Robert Spendlove, chairman of UPEC, pointed to factors such as a young existing work force and the nation's highest employment growth, along with Salt Lake Valley being one of the country's most undervalued real estate markets.

"All those tend to attract more people," Spendlove said.

Spendlove pointed to another factor in the 2005 estimates, which show migration outpacing the natural increase of 37,512, or the difference between births and deaths. There were 50,431 births in Utah in fiscal 2005, the first year since 1997 that wasn't record-setting, Spendlove said. It's also the first time since 1989 that births have declined since the previous year.

"It may mean that Utah's baby boom has peaked," Spendlove said.

Gov. Jon Huntsman Jr. said the growth means "more costs but also more sources of revenue if our economy grows and if we can create enough jobs here, higher-paying jobs."

"We should not fear population growth," Huntsman said. "It's inevitable. We should harness it appropriately."

Huntsman added that the state's estimated growth, which is outpacing census estimates, is a good sign for Utah gaining an additional congressional seat in 2010.

Utah had unsuccessfully filed a lawsuit claiming that 11,000 LDS Church missionaries living overseas should have been included in the 2000 Census after the state fell about 80 residents short of being allocated another seat in Congress.

"The numbers are certainly there," Huntsman said.

Perlich agreed, saying, "It's just a matter of mathematics. We'll definitely get a new seat."

Spendlove said while the federal numbers for 2005 aren't out yet, the state's population estimates have been higher than the Census Bureau's in the past.

Utah County and several cities in the county successfully challenged the Census Bureau's 2004 population estimates, raising the county's estimated population from 403,000 to 429,000. That's still about 2 percent lower than UPEC's estimates for the county.

Spendlove said Utah County is a more extreme example, but the statewide gap between federal and state population estimates has been widening slightly since 2001.

The state and census both use federal tax returns, along with birth and death certificates, to come up with estimates, he said. The state also uses other information such as school enrollment, LDS Church records and housing growth.

While the Utah estimates have shown strong net in-migration since 2000, the census estimates have shown that while Utah is gaining about 10,000 international migrants each year, it's also showing internally more people moving out of Utah than into the state.

"We don't know exactly what the decennial census will come up with," Spendlove said. "I feel very confident in the methods the Population Estimates Committee uses. . . . It's made up of local and state experts who know about what's happening with the population, what's happening on the ground."

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