Introduction and Executive Summary In recent months, leading politicians and policymakers have renewed calls for mass deportations of immigrants from the United States. While similar promises have been made in the past without coming to fruition"during the 2016 presidential campaign, for example, Donald Trump pledged to create a "deportation force" to round up undocumented immigrants "mass deportation now occupies a standing role in the rhetoric of leading immigration hawks. To cite just one example, former U.S. Immigration and Customs Enforcement (ICE) director Tom Homan has promised "a historic deportation operation" should a hawkish administration return to power.While some plans have envisioned a one-time, massive operation designed to round up, detain, and deport the undocumented population en masse, others have envisioned starting from a baseline of one million deportations per year.