Immigration enforcement is increasingly dependent on local criminal justice authorities, and yet basic questions on the criminal case processing of non-U.S. citizens in state and local jurisdictions remain unanswered. Leveraging uniquely rich case information on all felony arrests in California and Texas between 2006 and 2018, this article provides a detailed examination of the legal treatment of non-U.S. citizens from booking through sentencing. In both states, we find that non-U.S. citizens arrested for the same crime and with the same prior record are significantly more likely to be convicted and incarcerated than U.S. citizens. These unexplained citizenship gaps often exceed the observed disparities between white and minority defendants, but the results were not identical in both states. In line with the more rigid views towards migrant criminality in Texas, the case processing of foreign nationals is notably more severe there than in California at nearly every key decision point. These findings suggest that even in local criminal justice settings, citizenship is a unique and consequential axis of contemporary legal inequality.