Abstract This article examines drivers of state-level variation in interior immigration enforcement rates from 2015 through 2019. Combining analysis of administrative data on ICE apprehensions with in-depth interviews with immigration attorneys and advocates in a higher-enforcement state (New Hampshire) and a lower-enforcement state (Massachusetts), results move beyond the existing scholarly focus on on-the-books restrictive policies and police-ICE partnerships to reveal a multi-level set of factors that interact to shape the scale of immigration enforcement in U.S. states and the extent of variation between states in enforcement rates. These factors include: 1) executive branch policy regarding prosecutorial discretion power, 2) the orientation of law enforcement agencies towards cooperating with ICE (i.e., proactive versus restrained), 3) the landscape of state and municipal-level policies governing police-ICE cooperation, and 4) the strength of legal mobilization by state and civil society actors. This study’s findings further underscore the deeply unsettled and contested nature of the contemporary immigration enforcement field and have important implications for understanding enforcement dynamics during President Trump’s second term.
Margot Moinester (2025) studied this question.