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."