While garnering heightened attention following the Trump administration's travel restrictions, exclusionary tactics in counterterrorism have a much lengthier history. Given that some terrorism studies scholars identify social and political exclusion as an explanation for the resort to terrorist violence, the selection of a strategy of exclusion is significant. In this article, I identify the elements of a strategy of exclusion and the logic behind this strategy. In particular, I examine the origins and persistence of this strategy in the U.S. context. Rather than a contemporary anomaly, exclusion was among the first strategies the United States added to its counterterrorist tool-kit, and has remained among the most consistent strategies relied on. I trace the history of this strategy from its origins in immigration restrictions passed following the assassination of President McKinley by an anarchist through the contemporary War on Terror. Controversy surrounding this strategy, its negative effects on nonviolent immigrant populations, and its failure to prevent further acts of terrorism suggest it was historically ineffective and may also be so today.