We find that driving fatalities increased significantly following the terrorist attacks of September 11, 2001, an event which prompted many travelers to substitute less-safe surface transportation for safer air transportation. After controlling for time trends, weather, road conditions, and other factors, we attribute an increase of 242 driving fatalities per month to additional road travel undertaken in response to 9/11. In total, our results suggest that about 1,200 driving deaths are

more »

... able to the effect of 9/11. We also provide evidence that is consistent with the 9/11 effect on driving fatalities weakening over time as drivers return to flying. Our results show that the public response to terrorist threats can create unintended consequences that rival the attacks themselves in severity.