The Department of Homeland Security has limited ability to track migrants’ post-release addresses accurately and effectively. U.S. Border Patrol (USBP) cannot always obtain and does not always record migrant addresses, and U.S. Immigration and Customs Enforcement (ICE) does not always validate migrant addresses prior to migrant release into the United States. Based on our review of 981,671 migrant records documented by USBP from March 2021 through August 2022, addresses for more than 177,000 migrant records were either missing, invalid for delivery, or not legitimate residential locations. In addition to migrants not providing U.S. release addresses, DHS faced several challenges hindering its ability to record and validate migrant addresses as required. USBP did not accurately and effectively capture valid addresses, in part due to the large number of migrants apprehended, as well as its limited coordination with ICE and its limited authority to administer compliance with address requirements. ICE also did not have adequate resources to validate and analyze migrants’ post-release addresses.