News coverage and mass shootings in the US

We study the potential effect of mass-shooting-related television news in the US on subsequent mass shootings from 2006-2017. To circumvent endogeneity, our identification strategy relies on unpredictable disasters in countries home to substantial numbers of US emigrants crowding out shooting news. Instrumental variable and reduced form regressions consistently suggest a positive and statistically significant effect. This result remains consistent throughout a battery of robustness checks. In terms of magnitude, a one standard deviation increase in shooting news raises mass shootings by approximately 73% of a standard deviation. We then explore potential mechanisms, broadly delineating (i) the ideation of murder, (ii) fame seeking, and (iii) behavioral contagion. The number of murders in general remains orthogonal to shooting news, and mass shootings are not more likely on days with predictable news pressure (e.g., during the Olympics or the Super Bowl). However, mass shootings are more likely after anniversaries of the most deadly historical mass shootings. Taken together, these results lend support to a behavioral contagion mechanism following the public salience of mass shootings.