New documents found by the American Civil Liberties Union (ACLU) show that the Department of Homeland Security (DHS) used mobile location data to track people’s movements on a much bigger scale than was known before. It is not a secret that the U.S. has been getting and using data from Americans’ smartphones about where they are. Early in 2020, a report in a journal said that both Immigration and Customs Enforcement (ICE) and Customs and Border Protection (CBP) had bought access to the location data of millions of smartphone users in order to find undocumented immigrants and people who might be avoiding paying taxes.

But new documents that the ACLU got through a Freedom of Information Act (FOIA) lawsuit show how much data was collected without a warrant. The more than 6,000 records that the civil rights group looked at had about 336,000 location points from people’s phones all over North America. They also show that CBP got records for around 113,654 location points in the southwestern United States in just three days in 2018. That’s more than 26 location points per minute. Most of the information that CBP got from its contract with Venntel, a location data broker that collects and sells information that is secretly taken from smartphone apps, came from that contract. By buying this information from data brokers, officials get around the legal steps they would normally have to take to get their hands on cell phone data.