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For nearly two decades, Utah's population continued to rise while the percentage of its people who are Mormon slowly and steadily declined. Then the recession hit, jobs dried up and people hunkered down.

Utah's population is 62.2 percent LDS and that percentage hasn't moved much in the past three years.

That makes sense to Pam Perlich, a demographer for the University of Utah, who says the state has become less Mormon over time because people of other persuasions have moved here for economic opportunities.

"And we haven't had much migration to the state in three or four years," she noted.

The census estimates that Utah added 40,800 residents in 2011, but less than 10 percent of them were people moving here.

That means the growth in population is all about Utahns having babies and in this scenario, "you would assume there would be more stability in characteristics," said Juliette Tennert, the state's chief economist.

Utah was 62.1 percent LDS in 2009 and 2010, with a tiny bump in 2011, which Perlich calls statistically irrelevant because of potential sampling errors.

"It's flat," she said

And many counties saw only slight changes, if any, although Utah's two largest counties appear headed in opposite directions. Salt Lake County, with more than 1 million residents, went from 51.6 percent Mormon in 2009 to 51.4 percent in 2011.

Utah County, with a population of 530,500 residents, went from 80.9 percent in 2009 to 81.2 percent last year.

Perlich suggested Utah County's modest gain could be attributed to Utah Valley University's spike in enrollment after turning into a four-year institution. It has a predominantly Mormon student body, who are in their childbearing years.

Utah County added 10,450 residents from July 1, 2010, to July 1, 2011, and The Church of Jesus Christ of Latter-day Saints said 9,315 of them are members of that faith, accounting for nearly 90 percent of the total growth.

Salt Lake County added 15,075 residents and 7,324 of them are Mormons, or about 48.6 percent of the total.

If these trends hold, Utah County would become more LDS over time and Salt Lake County would eventually become minority Mormon. The state now has four counties where less than half of its residents are on the LDS Church rolls. They are Carbon, Grand, San Juan and Summit.

Utah County is one of just three counties that top the 80 percent threshold, with the others being northern Utah's Morgan and Rich.

The Salt Lake Tribune tracks the Mormon population using county-level membership numbers the church gives to state officials for demographic purposes.

The numbers include everyone on LDS membership rolls, which includes people who do not consider themselves Mormons or people who were lost "in transit." The LDS Church counts people who move in their last known address until they are either located or until they would have reached the age of 110.

In the past, The Tribune has compared these LDS membership numbers to state population estimates. But the Utah Population Estimates Committee has not met since the federal government released the 2010 census.

The official census showed Utah had fewer people than demographers had expected.

As a consequence, past estimates made Utah appear slightly less LDS than it actually was. Using 2009 state estimates, The Tribune reported that Utah was 60.4 percent LDS, when the census count showed it was really 62.1 percent.

"What we are seeing here is just that the last decade was really difficult to estimate," said Tennert, a member of the Utah Population Estimates Committee.

She noted the decade started with a recession leading to boom times in the mid-2000, which ultimately ended with one of the worst recessions in the nation's history. While demographers have a good handle on the births and deaths in the state, estimating those moving in and out proved difficult.

"We anticipated that there was more economic in-migration than there was," said Tennert.

Utah's economy has seen signs of revival in recent months and a reduction in unemployment. Perlich said that a return to growth also would likely result in a return to the trend observed since at least the late 1980s — a slow reduction in the share of Utahns who are members of the predominant faith. Twitter: @mattcanham —

Utah's LDS population

A look at the counties with the highest and lowest concentration of Mormons in 2011.

Top 5

Morgan County

Population 9,685

LDS percentage 86.1%

Rich County

Population 2,303

LDS percentage 83.3%

Utah County

Population 530,499

LDS percentage 81.2%

Sevier County

Population 20,971

LDS percentage 77.3%

Box Elder County

Population 50,290

LDS percentage 77.2%

Bottom 5

Grand County

Population 9,325

LDS percentage 26.5%

Summit County

Population 37,594

LDS percentage 30.8%

San Juan County

Population 14,825

LDS percentage 39.6%

Carbon County

Population 21,318

LDS percentage 45.9%

Salt Lake County

Population 1,048,985

LDS percentage 51.4%