Despite the centrality of Mexico–US border policing to pre- and post-9/11 US immigration geopolitics, perhaps the most significant yet largely ignored immigration-related fallout of the so-called war on terrorism has been the extension of interior immigration policing practices away from the southwest border. As I outline in this paper, these interior spaces of immigration geopolitics—nominally said to be about fighting terrorism, but in practice concerned with undocumented labor migration across the Mexico–US border—have not emerged accidentally. Rather, the recent criminalization of immigration law, the sequestering of immigration enforcement from court oversight and the enrollment of proxy immigration officers at sub-state scales have been actively pursued so as to make interior enforcement newly central to US immigration geopolitics. I argue here that these embryonic spaces of localized immigration geopolitics shed new light on the spatiality of US immigration governance, which has typically been thought of by geographers as active predominantly at the territorial margins of the state. I conclude the paper with some thoughts as to how geographers might rethink the what and where of contemporary US immigration geopolitics.