Immigrant Detention Numbers Fall Under Biden, But Border Book-Ins Rise
As of the end of President Biden's first full month in office, the number of individuals arrested by ICE and booked into civil immigrant detention fell sharply from 5,119 ICE book-in arrests during January 2021 to just 1,970 during February 2021. According to the latest ICE figures, this was a drop of 62 percent just in a single month. See Figure 1.
Figure 1. Book-Ins to Detention Drop Sharply in February 2021 But Trends Differ for Interior (ICE) vs Border (CBP) Arrests
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In contrast, those turned over to ICE for detention from arrests by the Border Patrol and at ports of entry climbed, from 3,024 to 4,696 in February after the Biden administration began allowing a limited numbers of families and adults, particularly those seeking asylum, to enter the United States. These figures do not include the growing numbers of unaccompanied children seeking entry along the southwest border, because children are turned over to the Department of Health and Human Services (HHS) rather than to ICE for custody pending their placement with relatives or adult sponsors.
Individuals Assigned to the MPP Program
Among these beginning to be allowed into the country were individuals arrested much earlier and forced to remain in Mexico awaiting court hearings. As they entered the country, some were temporarily held in ICE custody as they were being processed. Court records indicate that there were 29,177 individuals with active cases originally assigned to the MPP program at the end of February. During February, these data recorded that very few individuals (137) were reassigned to regular courts around the country. However, Court records likely undercount actual numbers given delays that often occur in keeping the Court's database updated.
As for family units involved, while ICE reported a widespread movement to release families from custody within the U.S., the average daily population of those held in ICE family detention facilities still rose modestly from 335 in January to 499 in February. The data do not identify how many of these had been originally assigned to the MPP program.
Number in ICE Detention Now At Record Low
At the end of February 2021, ICE reported a record low of only 13,529 in ICE detention. Around half of the people being held in detention had cases pending before the Immigration Court. Case-by-case data from the Immigration Courts indicated a total of 7,097 individuals of those detained had pending cases before the court at the end of February 2021. An alternative estimate from ICE reported 6,566 of those detained had been issued Notices to Appear which normally are used to initiate Immigration Court proceedings. See Table 1 at end of the report. Procedures underway for an additional 750 were not given.
The other approximately half of the detained population were being held after DHS issued expedited removal orders (4,725) or in cases where ICE was reinstating prior deportation orders (1,488) when these individuals were arrested after re-entering the country.
Trends in ICE Arrest Book-Ins and Detention
Over the last 29 months, ICE detention book-ins have been largely driven by what has been happening along the border. Detention book-ins from ICE arrests in the interior of the country were surprisingly stable, averaging around 11,000 per month until the pandemic struck. Then ICE arrest book-ins fell nearly by half and hoovered in round numbers around 6,000 monthly. Detention book-ins from CBP arrests at the border dropped even more precipitously as Trump administration policies turned individuals attempting to enter the country around and forced them back into Mexico. See Figure 2 and TRAC's previous report on the decline in criminal prosecutions under Title 42.
Figure 2. ICE Detention Book-Ins by Original Arresting Agency, October 2018 - February 2021.
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Book-ins tell only part of the story. Numbers in ICE detention also rise and fall depending upon how quickly individuals are booked-out either after being released from ICE custody or deported. Figure 3 shows the average daily population in ICE detention facilities by month for the same period of October 2018 through February 2021. While total ICE detention counts have varied markedly, these have been largely driven by the variation in the number of people turned over to ICE custody from border arrests.
Those remaining in ICE custody from ICE interior arrests changed only modestly between October 2018 when they were 21,368 and March 2020 when they were 19,174, before falling more sharply after the pandemic hit. Currently 60 percent of those who were in ICE detention facilities during February 2021 had been booked into custody from ICE interior arrests. See Figure 3. Monthly counts are presented in Table 2 at the end of the report.
Figure 3. Average Daily Population in ICE Detention by Original Arresting Authority, October 2018 - February 2021.
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 During the life of the MPP program, some 2,988 individuals as of the end of January 2021 had already been allowed to transfer their proceedings to non-MPP hearing locations within the country.
 Identifying the number of people in detention who have a pending immigration court case is complicated by the fact that detention status is not always reliably recorded in Immigration Court CASE files. Further, unaccompanied children held in HHS facilities are not included in ICE figures but would be included in Court counts if they had pending cases there.