Local Immigration Enforcement and Police Behavior at Traffic Stops: Evidence from the Texas Highway Patrol

Abstract

U.S. immigration enforcement increasingly relies on coordination with local and state law enforcement, which may induce shifts in day-to-day police behavior. Using data on 17 million traffic stops by the Texas Highway Patrol, I first document an increase in stops and citations of Hispanic drivers during a period of intensifying immigration enforcement, and provide suggestive evidence that increased stops may reflect efforts of pro-enforcement officers to participate indirectly in the deportation process. I then estimate the causal effect of increased enforcement by exploiting the staggered rollout of the Secure Communities program, which requires that county jails identify undocumented immigrants using a federal database. After accounting for smooth trends in Hispanic and white outcomes, triple-difference event study estimates suggest that Secure Communities does not significantly impact stops, searches, or citations of Hispanic drivers. Using a framework inspired by Knowles, Persico and Todd (2001), I show that immigration enforcement may affect stops through both police and driver behavior, but that any driver response should be small. I conclude that Secure Communities has little to no effect on the traffic stop behavior of the average state police officer.