In 22 of the state's 29 counties, that percentage rose last year. The biggest driver appears to be the reduction in people moving to the state since the economic collapse in late 2007 and early 2008, according to demographer Pam Perlich at the University of Utah.
Before that, The Tribune had tracked a long, slow descent in the percentage of Utahns on Mormon membership rolls.
Since 2009, that trend has reversed, and the LDS percentage has been inching up. In 2005, more than 36,000 people moved into Utah, according to statistics compiled by Perlich. That influx dropped to below 5,000 a year this decade.
The state's population has increased far more than that, driven by Utah's highest-in-the-nation birthrate. In 2013, Utah added 46,000 people, according to the Census Bureau — 78 percent of them came from Utahns having children.
"A lot of that internal growth is going to be traditional Utah populations," said Perlich, noting that the fastest-growing cities dot northern Utah County and southern Salt Lake County, which she described as "Mormon enclaves."
She also noted that demographers increasingly have seen people self-segregate, and she hypothesizes that the growth in Utah and southern Salt Lake counties is partly based on Mormons moving there from other parts of the state.
The two counties, the state's most populous, have far different Mormon populations.
Utah County, home to LDS Church-owned Brigham Young University, is one of just three counties with a Mormon rate that tops 80 percent, and it has become increasingly LDS in recent years.
In 2013, the Salt Lake City-based faith reported adding 12,815 members in Utah County. That number is startling, given that the Census Bureau estimated the county's overall population rose only 11,300 that year. Utah County is 82.26 percent Mormon.
For years, Salt Lake County had seen its LDS percentage decline. It appeared to be on track to become Utah's fifth county with a minority Mormon population when its LDS percentage dipped to 51.32 percent in 2012. But it bucked the trend in 2013 and saw its percentage rise to 51.41 as the LDS Church recorded an increase of 9,061 members.
South Jordan Mayor David Alvord was surprised by the numbers, having assumed Salt Lake County would continue to become more religiously diverse. But he's not disappointed.
Alvord, a Mormon and mayor of the county's fastest-growing city, said he hopes to see that LDS percentage climb.
"As a devout member, I would hope that trend would continue," he said. "I think the church is a good influence on communities."