DENVER — During President Donald Trump’s first year back in office, 4,750 people without legal status were arrested by federal immigration authorities in Colorado, new data shows, reflecting a near-quadrupling of the prior year’s arrest rate.

The data provides detailed insights into the dramatic effects of the Trump administration’s mass arrest and deportation efforts in the state and across the country — what one immigration attorney previously described as the federal government’s “deportation machine.”

The share of arrestees who have criminal convictions has plummeted, the data shows, while deportations of those with no criminal history have surged, despite federal officials’ claims that they’re pursuing the “worst of the worst.” The Denver Post analyzed U.S. Immigration and Customs Enforcement data that was obtained and processed by the Data Deportation Project. It included arrests in the full year ending Jan. 20, the anniversary of the start of Trump’s second term.

Of the thousands arrested in the state, 78% had a listed date of departure — indicating that they had already been removed from the United States.

The people arrested in Colorado came from more than 80 countries spread across five continents. Two thousand and one came from Mexico and 782 from Venezuela. Among others, 316 were from Guatemala, 22 from China, a dozen from Afghanistan and four from the United Kingdom.

They ranged in age from a 91-year-old Mexican man deported last year to two children who were, at most, a year old; one of them has also been deported, the data shows. At least 121 people were younger than 18. Ten of the arrestees were Iranians, all arrested within days of the United States’ first bombing campaign against that country in June.

Five Venezuelans were removed under the statute created by the Alien Enemies Act, the 18th-century law Trump used to send people to a notorious prison in El Salvador. All five were transferred to a Texas facility and then were removed on March 15, 2025, the data set shows. The men then disappear from the data. On that same day, nearly 300 people were sent to the prison in El Salvador from the same Texas detention center, according to the American Immigration Council.

In the 12 months prior to Trump’s inauguration in January 2025, 1,202 immigrants without legal status were arrested in Colorado. More than 58% of them had prior criminal convictions, while nearly 24% more had pending charges. Only 17.7% had no criminal history.

Looking at the Trump-era arrests, those trends flipped. Of the 4,750 people arrested over the ensuing 12 months, the largest group — 38% — had no criminal history, compared to nearly 35% with prior convictions and 26% with pending charges.

Surge in ICE presence, arrests

The Post analyzed ICE arrest and detention data obtained and released in full by the Deportation Data Project, which is composed of researchers and lawyers based primarily at the University of California, Berkeley.

For the purposes of its analysis, the Post examined arrests that occurred in Colorado during the 12-month period that began when Trump returned to office on Jan. 20, 2025, and compared it to arrests made during President Joe Biden’s final year in office.

The Deportation Data Project, using data obtained from public records requests, has released four broad batches of ICE data detailing arrests and detentions since Trump’s return to office. ICE has released far more limited information on its operations, often focusing on arrests of immigrants with criminal backgrounds.

Using unique identifiers attached to each arrestee, the Post excluded a number of apparent duplicate arrests from its analysis. In both 2024 and 2025, the Post examined only the arrests that the data identified as occurring in Colorado or at a specific location within the state.

The Post used publicly available information and multiple datasets to match more than a dozen specific arrests — of a Colombian family from Durango; of a Brazilian-born college student on I-70; of a Peruvian school teacher and her family; of a Nicaraguan man arrested in Dillon who later died in a Mississippi detention center — to corresponding entries in the Berkeley data.

The surge in arrests came as ICE has significantly ramped up its presence in the state. Gregory Davies, a senior ICE official in Denver, testified in court last month that the number of deportation officers in the area has more than doubled — to roughly 200 — since Trump’s return to office. The Denver field office also has responsibility for Wyoming.

A recent New York Times analysis of internal ICE data identified more than 5,200 ICE arrests in Colorado and Wyoming between Trump’s inauguration and mid-December. In the Denver area, the Times found, arrests peaked last summer and have declined since.

The Post’s analysis found a similar trend in Colorado: There were more than 500 arrests in both June and July, averaging more than 17 per day. Over the fall and winter, they dropped, averaging between 12 and 14 per day.

The ICE detention center in Aurora has flexed its capacity to the maximum possible and can now hold more than 1,500 detainees, according to federal contracting records. When Trump was inaugurated, the facility held just over 1,000 people. By the end of the year, its daily population regularly topped 1,400, the Berkeley data shows.

Federal officials have also pursued plans to open one or more additional detention facilities in Colorado.

In an unsigned statement Thursday, the Department of Homeland Security said the data — which was obtained by the data project through public records requests — “is not accurate.” An unidentified media office representative did not say what part of the data was incorrect and did not directly address questions about the Post’s findings.

“The facts are: ICE is targeting criminal illegal aliens including murderers, rapists, criminals, gang members and more,” the DHS representative wrote in an email to the Post. “Nearly 70% of ICE arrests nationwide are of illegal aliens charged or convicted of a crime in the U.S.”

Numbers are ‘not at all surprising’

In October, attorneys suing ICE for its arrest practices questioned the now-former head of ICE’s Denver field office about a prior Post analysis of the Berkeley data. That official, Robert Guadian, said he didn’t know exact numbers but didn’t dispute the Post’s findings.

Davies, the other senior official, testified last month that the agency now averages between 15 and 25 arrests per day. The Post’s analysis shows ICE has arrested just under 15 people per day on average since late January of this year and 13 per day since the start of Trump’s term.

The findings also align with what immigrant-rights advocates and immigration attorneys are seeing in real time.

“They’re not at all surprising,” Laura Lunn, an immigration attorney with the Rocky Mountain Immigrant Advocacy Network, said of the numbers. “They’re (emotionally) deflating, but not surprising.”

“Obviously, so much has happened since this administration took over, but I think a lot of folks don’t necessarily remember that Trump announced Operation Aurora shortly (before) he took office,” she continued. “Communities in Denver and Aurora were targeted for mass enforcement actions. We saw military-grade vehicles rolling down the streets of Denver before we saw the same thing happening in L.A., Chicago, Minneapolis.”

The surge in arrests has led to an accompanying growth in deportations, particularly as federal officials have moved to keep immigrants detained indefinitely by, among other things, granting bail far less often to longtime residents of the United States.

Over the past year, according to earlier Post reporting, an unprecedented number of Aurora detainees have been granted voluntary departures — essentially deportations without a more punitive court order. More than 1,700 people have requested voluntary removals from the facility since the start of 2025, according to immigration court data published by researchers at Syracuse University — a level unparalleled by any period since the researchers began tracking it nearly 30 years ago.

Of the 4,750 people arrested in Colorado during Trump’s first year back in office, 3,710 have already left the United States, the Berkeley data shows.

More than 62% of those arrested and removed last year had never been convicted of a crime, while more than a third had no criminal history.

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