WASHINGTON - Immigration arrests in the interior of the United States fell in fiscal 2021 to the lowest level in more than a decade - roughly half the annual totals recorded during the Trump administration, according to U.S. Immigration and Customs Enforcement data obtained by The Washington Post.

Officers working for ICE's Enforcement and Removal Operations (ERO) made about 72,000 administrative arrests during the fiscal year that ended in September, down from 104,000 during the 2020 fiscal year and an average of 148,000 annually from 2017 through 2019.

ERO administrative arrest data is considered one of the best gauges of ICE activity because interior enforcement is entirely under the agency's control, unlike deportations and other metrics that rise and fall with migration trends at the Mexico border.

ICE arrests in the interior plunged after President Joe Biden took office and set new limits on immigration enforcement, including a 100-day "pause" on most deportations. A federal judge quickly blocked that order. But while ICE's arrests have increased in recent months, enforcement levels under Biden's new priority system remain lower than in previous years.

During the fiscal year that ended Sept. 30, ERO's 6,000 enforcement officers each averaged about 12 immigration arrests per year, or one per month. The peak of ICE enforcement activity during the past decade was fiscal 2011, when ICE made 322,093 administrative arrests, about 4.5 times the 2021 total, historical data show.

Asked for comment on the data, ICE spokeswoman Paige Hughes said the agency "is in the process of finalizing our year-end fiscal numbers, and these numbers will be shared publicly when the review is complete. Data integrity is of the utmost importance to the agency and ICE's vetted statistics powerfully demonstrate the effectiveness of our current approach of prioritizing national security, border security, and public safety."

Homeland Security Secretary Alejandro Mayorkas issued broad new directives to ICE in late September, telling officers the fact that someone is present in the United States illegally "should not alone be the basis" of a decision to detain and deport them. The new directives take effect Nov. 29.

But the agency months ago shifted away from the priorities of the Trump administration, with ICE officials saying officers are focused on arresting more serious criminals.

Under President Donald Trump, ICE officers had broad latitude to enforce immigration laws and make arrests, and many of those who were categorized as "criminal" suspects were nonviolent offenders or had convictions for immigration violations such as illegally reentering the country.

About 90% of those taken into custody by ICE officers during the 2020 fiscal year were convicted criminals or had pending criminal charges, according to agency data. That share fell to 65% during the 2021 fiscal year. The remaining one-third were "immigration violators," the data show.

ICE officials offered other data that they say reflects their new approach. Between Feb. 18 and Aug. 31, ICE arrested 6,046 individuals with aggravated felony convictions, compared with 3,575 in the same period in 2020, officials said.

They also pointed to the arrest of 363 sex offenders during a targeted operation this summer, compared with 194 during that period the previous year. Nearly 80% of these offenses involved child victims, ICE said.

Mayorkas's new ICE guidelines instruct officers to continue to prioritize immigrants who pose a threat to national security and public safety, as well as recent border-crossers who entered the United States illegally.

"Are we going to spend the time apprehending and removing the farmworker who is breaking his or her back to pick fruit that we all put on our tables?" Mayorkas told The Post in a September interview. "Because if we pursue that individual, we will not be spending those same resources on somebody who does, in fact, threaten our safety. And that is what this is about."

Mayorkas gave ICE officers wider discretion to determine whether to arrest someone, easing interim guidelines issued in February that required senior supervisors to sign off on street-level enforcement decisions.

Jessica Vaughan, director of policy studies at the Center for Immigration Studies, which favors reducing immigration, accused ICE of a "collapse in interior enforcement," even as the agency continues to receive billions of dollars for detention and deportations.

"This is a public safety problem that we don't need to have," she said, adding that one officer told her "the hardest part of my job now is pretending to look busy."

Illegal border crossings have soared since Biden took office, and the 1.7 million migrants apprehended by the Border Patrol during the 2021 fiscal year was an all-time high. Critics of the Biden administration say lax interior enforcement has incentivized illegal entries.

ICE curbed some enforcement activity in 2020 to avoid the spread of the coronavirus inside immigration jails. In the months that followed, the detainee population dropped to the lowest levels in more than a decade. The current detainee population is about 22,000, according to the most recent agency statistics, well below the peak of more than 56,000 during the Trump administration.

The Biden administration is also facing a backlash from immigrant advocacy groups. They are angry over the mass expulsion of Haitian migrants last month from a makeshift camp in Del Rio, Texas, as well as plans to restart the Trump-era "Remain in Mexico" policy in November, which a federal court has ordered.

Activists protested by staging a virtual "walkout" from a meeting with top Biden immigration advisers this month, with many saying his enforcement approach is no different than his predecessor's.

And while advocates for immigrants say they are encouraged by the shift in interior enforcement, they are unsure how the Department of Homeland Security will monitor ICE's compliance with the priorities taking effect next month.

Maru Mora Villalpando, a 50-year-old Mexican national living in Washington state, said the new policies marked "a major victory" for grass-roots immigration organizations that have been fighting to limit arrests.

She said the Trump administration targeted her for deportation after she publicized detainee protests in her state, though she had no criminal record and her daughter is a U.S. citizen. She said she overstayed a visa and has lived here since 1996.

The Biden administration, in contrast, exercised its prosecutorial discretion to set aside her case this year, clearing the way for her daughter to sponsor her for legal residency, she said. A few days ago, she said, her green card arrived.

DHS also said this month that the agency would discontinue mass roundups at worksites and more aggressively target unscrupulous employers who exploit unauthorized immigrants.

"This work that we've done for so many years is paying off today," said Mora Villalpando, who is still organizing help for detainees in Washington state, which recently passed a law to phase out private detention centers.

"I'm one of the lucky ones," she said. She is planning to return home to Mexico soon to visit siblings she hasn't seen in 25 years; her parents have already died.

“I just couldn’t believe it,” she said of getting her green card, but added: “This doesn’t end with me having a green card. . . . The work will be done when ICE is no more.”