The number of undocumented immigrants living in the United States dropped by 1.2 million over the past eight years as new arrivals were outnumbered by those choosing to return home. But Utah is an exception to that trend.

The number of undocumented immigrants living here increased slightly from an estimated 91,000 to 92,000 between 2010 and 2018, according to a new report from The Center for Migration Studies.

“Really, that’s flat” growth, said Pam Perlich, senior demographer at the University of Utah’s Kem C. Gardner Policy Institute. She said an increase of just 1,000 over eight years “is so small that it’s almost just noise” in the data.

Still, whether growth is flat or up slightly, it is different than most of the nation. Perlich says she sees one major reason for that.

“It’s the economy here,” she said. “We have pretty consistently been among the most rapidly growing in terms of jobs.” And new immigrants tend to go where the jobs are.

She said job demand in Utah has been especially strong in construction and the hospitality industies — two areas that tend to attract undocumented immigrants.

For example, Salt Lake City’s Airport Advisory Board heard a report last week that it continues to struggle to find enough construction workers for its $4.1 billion project to rebuild the international airport. It figures it has enough labor to keep on schedule to open its first phase in September but could always use more — especially electricians who are in short supply.

Utah’s unemployment rate hit an all-time low of 2.3% in December, which was a third lower than the national average. Utah also led the nation for the percentage of new jobs created in 2019, 3.1%, which was more than double the national average.

Also, a recent U.S. Chamber of Commerce study said that for every three open jobs in Utah, only about two workers are available. That’s the fifth lowest ratio in America.

The new Center for Migration Studies report said improving conditions in home countries — drawing undocumented immigrants back home — is helping to reduce the number of undocumented immigrants living in America.

“There’s a widespread assumption that everyone wants to come to the United States and no one ever leaves, but that’s never been true,” said report author Robert Warren. “There’s always been a return flow, but until recently we weren’t able to measure it well in the undocumented population.’

The report estimates that the undocumented population was 10.6 million in 2018, down by 1.2 million since 2010 or 10%.

The undocumented population from Mexico fell from 6.6 million in 2010 to 5.1 million in 2018, a decline of 1.5 million, or 23%, the study said.

Some of the other key finding from the study include:

• Since 2010, about two-thirds of new undocumented immigrants arrived by overstaying temporary visas, while a third entered illegally across the border.

• The number of undocumented immigrants from El Salvador, Guatemala and Honduras remained at about the same level in 2018 as the previous four years despite high numbers of Border Patrol apprehensions of people from those countries in recent years.

• Two countries had especially large undocumented population changes — in different directions — from 2010 to 2018. The population from Poland dropped steadily, from 93,000 to 39,000, while the population from Venezuela increased from 65,000 to 172,000. Political unrest in Venezuela appears to have added more than 100,000 to the U.S. undocumented population in just four years.

• Counter to normal intuition, the number of undocumented immigrants dropped fastest from 2010 to 2018 in states that cooperate the least with federal immigration enforcement efforts: New York ( down 25%), Illinois ( down 24%), and California (down 21%). Meanwhile, the number of undocumented immigrants in Texas, which is not a so-called “sanctuary state,” continued to grow.