Only one city of comparable size can match the rise and fall of Salt Lake City's workday population, according to new census figures released Thursday.

Salt Lake City may have about 180,000 full-time residents, but when you add the commuters, the city population surges to around 313,000.

Only Irvine, Calif., sees its population rise at a sharper rate on workdays, when comparing cities that have at least 100,000 residents.

In Utah, Park City has the highest rate of daytime commuters, nearly doubling in size as workers fill the shops and offices of the skiing town. Park City is followed by South Salt Lake and then Salt Lake City.

In Utah's capital, about 26,000 residents leave to work in another city while 160,000 people commute into Salt Lake, making it by far the largest numerical increase, according to Pam Perlich, an economist for the University of Utah's Bureau of Economic and Business Research.

"The resident population for Salt Lake City is deceptively low," said Robert Spendlove, lead demographer for the state planning office.

Those figures ignore people like Scott Brown, the head of global business for a downtown software company.

Every morning, he takes the 35-minute drive from his Lehi home to his Salt Lake City office.

"Compared to most cities, it's nothing," he said of the commute.

He built a new home last year at the northern tip of Utah County to be closer to his parents and his in-laws. He also was able to build a big home for relatively low cost.

The southern part of Salt Lake County and northern Utah County continue to expand rapidly and have become a magnet for commuters.

Brown's town of Lehi actually sees its population shrink by 17.8 percent during the workday.

Other than his frequent lunches in the big city and the occasional play or Utah Jazz game, Brown stays close to home.

He shops in Sandy, primarily.

"If you want to go to the mall, there is a mall in every city," he said.

Salt Lake City officials would love to see more people like Brown and his family uprooting to their town. They would make for a livelier city on weekends and nights. And they would also pay property taxes, the city's top source of revenue.

Then there's the impact on the environment.

"Having people living closer to where they work, that's better for everybody," said Alison McFarlane, Salt Lake City Mayor Rocky Anderson's economic development adviser. "The less people commuting, the less people driving in their cars, the better the air quality."

Nevertheless, the city welcomes the daytime visitors, hoping they grab lunch at the local eatery and stop to shop before heading home. Sales tax, after all, is the city's second-largest revenue source.

"If we didn't have a downtown, if we didn't have buildings that had 500 people working in them, we'd be like any other city," said Steve Fawcett, deputy director of the city's Management Services. "We obviously wouldn't be able to afford the same level of service, there would have to be some major adjustments."

He can't say whether the large daytime population poses a financial burden on city services, or if those people pay their share through sales taxes. The city does provide those commuters with some services - from crews repairing worn roads to police responding to car prowls in the office parking garages.

The Police Department hinges its request for 90 more officers by 2010 on the need to handle a growing daytime population.

"We can't not run on a medical call, if a commuter has a heart attack well, too bad," Fawcett said. "It's intuitive, they do demand services. But I can't say unequivocally that they either are a drain or that they contribute their fair share. It's a great big no-answer."