Immigration enforcement in Northern California reached a new high this summer, with more immigrants arrested in July than in any other month during the second Trump administration.
Nearly 900 people were arrested in Northern California in July, and some 440 of them were booked into Immigration and Customs Enforcement detention, according to a Mission Local analysis of data released this week by the Deportation Data Project, a research group spearheaded at the University of California, Berkeley.
That’s compared to around 800 arrests in June and 600 in May, an uptick that follows a decrease in arrests this past spring. Immigrants with no criminal history continue to account for the largest share of those arrested.
The numbers match national totals of soaring arrests across the country as ICE strives for 2,000 arrests per day. In July, 49,000 immigrants were arrested across the country, according to the data from the Deportation Data Project.
Compared to other jurisdictions, the number of arrests and book-ins to detention facilities in Northern California is low: Those rates are highest in ICE jurisdictions along the U.S.-Mexico border, namely in Southern Texas and around San Diego.
The totals cover all “administrative arrests,” a term used by ICE that lumps together physical arrests — such as those widely covered by Mission Local and other outlets that take place at San Francisco International Airport or immigration courthouses — together with cases where someone is put into removal proceedings but not physically detained.
That may help explain why, though the data shows more immigrants were arrested, fewer of them were taken into ICE detention facilities.
Between May and July, almost half of those arrested in Northern California had no corresponding detention record, suggesting that they weren’t kept in ICE custody. The gap between those arrested and those detained goes back to December of last year.
Though it was not clear why fewer immigrants were taken to detention centers, Phil Neff, a researcher with the Deportation Data Project, said the trend is also visible in other regions. According to the data, those regions include Florida; Harlingen, Texas; and San Diego, California.
Claire Trickler-McNulty, a former senior ICE official, said the gap may also be due to immigrants being placed into “alternatives to detention” programs instead of detention.
These programs often involve surveillance. Immigrants are released from detention, but remain under ICE supervision through mobile app check-ins, ankle or wrist-worn monitors.
As of July, in the San Francisco “area of responsibility,” which covers Northern California, Hawaii, Guam and Saipan, there were 20,804 active participants under the “alternatives to detention” program, more than any other jurisdiction in the country.
The dip in detention book-ins may also be related to a court order prohibiting ICE from detaining immigrants while their asylum case is processed.
For the first time, the data also includes information on the city where an arrest happened. Although monthly arrest levels have increased regionally and nationwide, the number of arrests in San Francisco did not pass 2025 levels.
In July, there were about 189 arrests, about a fifth of the total in Northern California. Most of those arrested in San Francisco this year were not booked into detention.
A spokesperson for ICE did not provide comment on the patterns observed in the data. “The UC Berkeley’s Data Deportation Project is an external organization that DHS cannot verify the source of, accuracy, completeness, or methodology of the data. The Deportation Data Project relies on information releases that have not been reviewed, audited or given context,” a spokesperson wrote in a statement. “The bottom line is that the Deportation Data Project is not accurate.”
The data provided by the Deportation Data Project was obtained through a records request to ICE and subsequent litigation.
