This study attempts to identify the major factors that have contributed to traffic safety in the past, with a view to help identify which approaches are likely to be most fruitful in the future. The study builds upon the author's 1987 study which addressed similarly broad questions that require judgmental synthesis rather than analysis. In the earlier paper all factors were classified into what were defined as ’human infrastructure‘ and ’engineering infrastructure‘. Although components of the engineering infrastructure (roadway, traffic engineering, vehicles) were demonstrated to make important contributions, it was concluded that the human infrastructure component was of even greater importance, with social norms making the largest contribution. The present paper examines traffic fatality rates for 12 countries over a 19-year period, and for the United States over a 68-year period. The observation that variations over time and country appear larger than can be attributed exclusively to engineering improvements suggests again that behavioral factors, especially social norms, are playing a large role. The major changes in public health that have resulted from collective behavior changes in smoking, exercise, diet and alcohol use suggest that further progress in traffic safety might be made by similar collective changes in driver behavior. The following items are judged worthy of additional study as possible stimulants to changing social norms in directions more conducive to traffic safety, and away from directions which are inimical to safety: (i) the effect of fictional television and movie portrayals of the lifethreatening use of motor vehicles as heroic or humorous, (ii) the effect of encouraging increased courtesy on the road, and (iii) the effect of social norms relating to alcohol, and the forces that shape such social norms.