Utah’s population grew by an estimated 52,664 people this year — equivalent to adding a city the size of Logan. But growth is slowing as Utahns have fewer children and immigration decelerates.

The state’s population now is 3,166,647, according to the Utah Population Committee, a group established by the state to use local data to estimate the population as a check on estimates produced by the U.S. Census Bureau.

Since the census in 2010, Utah has added 402,000 people — equivalent to adding two cities the size of Salt Lake City.

This year, “Utah’s 47,310 births are at the lowest level since 2000,” reflecting a recent state and national trend, Emily Harris, a demographic analyst at the University of Utah’s Kem C. Gardner Policy Institute, wrote in a report explaining the new estimates.

(Christopher Cherrington | The Salt Lake Tribune)
(Christopher Cherrington | The Salt Lake Tribune)

Still, Harris wrote, “Utah maintains one of the highest fertility rates,” which shows how many children a typical woman would have in her lifetime. “Utah’s total fertility rate (2.12 in 2017) is currently second to South Dakota (2.23 in 2017).”

Harris said Utah’s fertility rate started dropping during the Great Recession. “Utah’s total fertility rate has fallen from 2.45 in 2010 nearly to replacement level.”

Only two of Utah’s 29 counties — Wasatch and Juab — have seen a cumulative increase in births since 2010, the report said. Also, 26 counties have seen a rise in deaths since 2010 (all but Wayne, Beaver and Rich).

Since 1990, “natural increase” — or more births than deaths — accounted for about two-thirds of Utah’s population increase. But this year, it produced 56 percent of the growth.

Meanwhile, Utah had seen immigration expand every year since 2012. But “Utah’s net migration decreased in 2018 to 23,248 — below last year’s estimate by 3,843, or 14.2 percent. This is still significant in-migration to the state,” Harris said.

Summing all births, deaths and net in-migration, Utah’s growth this year was down by 6,325 people compared with 2017.

“Utah’s demographic growth is related to continued economic growth” — attracting more immigrants — “as well as positive natural increase,” said Pam Perlich, director of demographic research at the Gardner Policy Institute.

Among counties, Utah County had the largest jump in population this year with 15,847 new residents for a total population of 633,582.

That was higher than Salt Lake County’s increase of 13,806, for a total of 1,142,077 residents.

By percentage, Iron County — home of Cedar City — had the most rapid growth at 3.58 percent, followed by two other southwestern counties: Piute, at 3.45 percent, and Washington, 3.29 percent.

Counties that ring the Wasatch Front, and attract growth from it, also are experiencing significant growth, including Juab at 3.21 percent, Tooele at 2.57 percent and Wasatch at 2.93 percent.

Those trends are consistent with census estimates for 2017, when Wasatch, Tooele and Morgan counties were among the top 10 fastest-growing counties in the nation.

Also last year, St. George was the nation’s fastest-growing metropolitan area (while Provo-Orem was No. 8), and Heber was No. 1 among micropolitan areas of fewer than 50,000 residents.

Only two counties in the fast-growing state lost some population this year. Emery’s population dropped by 16 people to 10,668. Garfield dipped by 11 to 5,229.

“Emery’s population losses are due to people migrating out of the county, rather than natural decrease," Harris said. “Inversely, Garfield’s estimates show migration into the county, but a combination of declining births and increasing deaths outweigh the number of people moving in.”

Since 2010, Salt Lake County has boosted its population the most among the state’s counties — adding 112,422 people. But the fastest-growing by percentage in that time was Wasatch, swelling by 36.6 percent.

Emery County has seen the biggest population loss since 2010 — 308 people, or minus 2.8 percent.