Weather Impact on Racial Composition and Citation Activity of Traffic Stops in the United States

Research on the relationship between race and traffic stops is statistically challenging because available data sources only include information on those pulled over and not on those violating traffic laws. To overcome this issue, we analyze the impact of adverse weather on the racial distribution of traffic stops and citation issuance. Weather may affect racial bias if it becomes more “costly” for police officers to leave their patrol cars due to, for example, wet conditions. Using a data set including 37 city and 11 state police departments, we find that the racial distribution of drivers stopped and the probability of a citation being issues is not independent of adverse weather conditions. Regarding the racial distribution of stopped drivers, results for state police agencies are more pronounced than for city agencies. For state agencies, a drop to one-third of the “no rain” share of black drivers among those stopped is observed under very low temperatures and heavy precipitation. The probability of a citation being issued significantly increases with precipitation for state agencies but remains unchanged for city agencies. Our results add to the literature on factors influencing the interaction between citizen and police. In addition, the research serves as a possible starting point on how to reduce violent police encounters and officer-involved shootings