This study assesses the effectiveness of state regulatory efforts to improve traffic safety.

Methods. Annual data for the period 1967-1991 for all 50 states were analyzed through the use of pooled time series analysis.

Results. Mandatory seat belt laws, an increased minimum legal drinking age, and a 55-mph maximum speed limit were found to reduce state traffic fatality rates. Spending on road maintenance and police and safety functions also is an important policy tool for reducing motor vehicle fatalities.

Conclusions. These findings suggest that direct efforts by states to regulate driver behavior have resulted in improved traffic safety. Conversely, the trend toward greater maximum speed limits is contrary to the concern for safer highways.