Endogenous Driving Behavior in Tests of Racial Profiling

African-American motorists may adjust their driving in response to increased scrutiny by police. In daylight, when their race is more easily observable, minority motorists are the only group less likely to have fatal motor vehicle accidents. In Massachusetts and Tennessee, we find that African-Americans are the only group of stopped motorists with slower speeds in daylight. Consistent with an illustrative model, these speed shifts are concentrated at higher percentiles of the distribution. Calibration of this model indicates this behavior creates substantial bias in conventional tests of discrimination that rely on changes in the odds a stopped motorist is a minority