The population of immigrants illegally staying in America rose by more than 40,000 in just two years in Colorado, a new report has found.

In 2021, this population in Colorado was estimated to be 160,000. Just two years later, that figure had ballooned to more than 200,000, according to the Pew Research Center’s most recent report on the issue.

That number coincides with the dramatic increase of immigrants — mostly from South and Central America — that Denver started seeing after a busload was dropped off at Union Station in December 2022.

More than 43,000 have come since.

Jon Ewing, a spokesperson for Denver Mayor Mike Johnston, said he believes that Pew’s estimate would have captured most of the influx.

While city officials recorded the number of people who sought services — primarily temporary shelter and transportation — they did not track who stayed.

Bus, plane and train tickets for immigrants to travel elsewhere suggest that about half stayed.

“I think that the number today would be different,” Ewing said, noting that any population count is a point-in-time estimate. “It’d be lower.”

The size of the immigrant population illegally living in the U.S. hit a record of 14 million in 2023, according to Pew. That number marks two years of consecutive growth.

The previous high was in 2007, when Pew estimated there were 12.2 million in the U.S.

The Pew Research Center is a nonpartisan think tank that seeks to better inform the public about the issues that mold society by conducting public opinion polls, demographic and social science research, according to the organization.

Pew has been estimating the size and characteristics of this population for decades. In 2022, Pew estimated its size at 11.8 million.

“The increase from 2021 to 2023 was driven primarily by growth in the number of unauthorized immigrants who were living in the U.S. with some protections from deportation, such as immigrants paroled into the country and asylum seekers,” the report said.

About 6 million immigrants in 2023 had legal status with some protections from deportation. That’s more than double what it was in just two years earlier, when the U.S. had 2.7 million immigrants with protected status.

Both of these numbers reflected a sharp increase since 2007, when there were about 500,000 immigrants with some protections against deportation.

The study noted that the number of immigrants with temporary protections from deportation increased following changes the Biden administration adopted after 2021.

The immigrants unlawfully staying in the U.S. with some protections represent about 40% of those without any legal status in 2023, the study found.

The authors said policy decisions that began under former President Joe Biden and continued under the Trump administration — notably an end to accepting asylum applications at the southern border and pausing parole programs — has “slowed considerably” the growth in this population.

“As of mid-2025, the unauthorized immigrant population likely remains above 2023 levels,” the report said.

The full impact of these policy shifts won’t likely be known until more data is available, Pew researchers said.