Through a mixed-methods approach that draws on over 4000 pages of organizational documents and two quantitative data sets from federal and state entities, the authors ask, has the growth of electronic surveillance by local criminal justice agencies, with corresponding database interoperability and information sharing, changed how federal agencies—specifically immigration agencies—operate? We focus on the CalGang Database, California’s statewide gang intelligence database, to document how, since its inception in 1998, CalGang has grown both in the number of individuals under surveillance and the number of what we call adjacent users, which we define as people who can access CalGang data but were not initially intended as users and who, in pre-digital surveillance eras, would have a much more difficult time obtaining the information. In this paper we focus specifically on adjacent users in the immigration system who determine the detention and deportation of noncitizens by leveraging an information sharing agreement that gave U.S. Immigration and Customs Enforcement (ICE) access to Calgang between January 2006 and October 2016. Using a two-way “difference in differences” approach, we estimate the impact of CalGang interoperability on federal adjacent users by comparing outcomes across immigration cases that began before or after the data sharing agreement ended. Our qualitative and quantitative analyses both demonstrate that immigration adjudicators’ access to local electronic surveillance information is associated with an increase in the number of immigrants facing criminal immigration charges that do not necessarily require a formal criminal conviction in state court, and that deportation rates are higher when ICE has access to local electronic surveillance.