Variation in U.S. traffic safety policy environments and motor vehicle fatalities 1980-2010

Objective: To examine the impact of variation in state laws governing traffic safety on motor vehicle fatalities. Study design: Repeated cross sectional time series design. Methods: Fixed effects regression models estimate the relationship between state motor vehicle fatality rates and the strength of the state law environment for 50 states, 1980-2010. The strength of the state policy environment is measured by calculating the proportion of a set of 27 evidence-based laws in place each year. The effect of alcohol consumption on motor vehicle fatalities is estimated using a subset of alcohol laws as instrumental variables. Results: Once other risk factors are controlled in statistical models, states with stronger regulation of safer driving and driver/passenger protections had significantly lower motor vehicle fatality rates for all ages. Alcohol consumption was strongly associated with higher MVC death rates, as were state unemployment rates. Conclusions: Encouraging laggard states to adopt the full range of available laws could significantly reduce preventable traffic-related deaths in the U.S. - especially those among younger individuals. Estimating the relationship between different policy environments and health outcomes can quantify the result of policy gaps.