EAGLE MOUNTAIN — Eagle Mountain city officials say their town is growing so fast the U.S. Census can't keep up, while Provo wants to know why the government is shortchanging its population count.

According to U.S. Census estimates released last week, Eagle Mountain grew 21 percent in the past year, going from 6,102 residents to 7,405. The census says Provo, however, lost about 1,000 residents during the same time with an estimated 105,410 residents.

Even with Eagle Mountain's growth rate, the second largest in Utah, officials claim the numbers underestimate the actual population of the city by more than 2,000 people.

The difference, they say, is costing the city money since some state funds like road funds and gas tax revenues are allocated based on Census Bureau population estimates.

The state uses the numbers as a basis for how much money cities get from different tax revenue such as class B and C road funds or money from the gas tax, said Shawn Elliot, Mountainland Association of Governments transportation planner.

"For the bigger cities it may not be as big of a deal, but for a little town . . . it would make a big difference to their budget," he said.

Eagle Mountain City Administrator Chris Hillman said based on the number of new utility connections, there are more than 2,000 people unaccounted for in the 7,405 population number.

Currently, Hillman said the city has between 9,000 and 10,000 people and the city is still averaging between 300 and 400 building permits a year.

The U.S. Census Bureau makes a door-to-door count of the nation's population every 10 years, but it estimates population changes each year the census is not actually counted. The numbers are based on the 2000 Census and then adjusted, taking into account births, deaths and migration.

According to the latest U.S. Census Bureau figures, Herriman led the state with a 34 percent increase in the past year. The census estimated Herriman has 5,632 residents, up from last year's estimated count of 4,182.

But Herriman officials also say they have been shortchanged. Mayor J. Lynn Crane said the town's population was closer to 10,500.

In Provo, city leaders are trying to find out where 1,000 residents went in the past year.

"We are frankly surprised that they show a decrease," said city spokesman Michael Mower. "We don't know what they are looking at. All indications, especially with the fall population with all the students, show we continue to increase."

Elliot is encouraging cities to appeal the census numbers, but to do that, cities must prove the Census Bureau's figures are incorrect.