Over the past four decades, more than 2,300 people have been the victims of mass shootings in the United States. Research shows that mass shootings have significant detrimental effects on the direct victims and their families. However, relatively little is known about the extent to which the impacts of these tragedies are transmitted into communities where they occur, and how they influence people beyond those directly affected. This study uses nationally representative data from the restricted-access Gallup-Healthways survey to assess the spillover effects of mass shootings on community wellbeing and emotional health outcomes that capture community satisfaction, sense of safety, and levels of stress and worry. To our knowledge, our analysis represents the first nationwide investigation of the impact of mass shootings on the emotional health of people living in communities where these tragedies occur.

We leverage differences in the timing of mass shooting events across counties between 2008 and 2017. Specifically, we compare the community and emotional wellbeing of individuals who are interviewed by Gallup right after a mass shooting with those who are interviewed right before, in counties where shootings occur relative to other counties. We control for individuals' socio-demographic characteristics and month-by-year and county fixed effects in all specifications, thereby separating the impacts of the mass shootings from other existing trends in wellbeing.

Our results provide consistent evidence that mass shootings have adverse effects on the emotional and community wellbeing of American adults. Specifically, we find that a mass shooting reduces the probability of having excellent community wellbeing by 27 percentage points and the probability of having excellent emotional health by 13 percentage points four weeks following the incident. We conduct event study tests which confirm that our treatment and control groups followed common trends before the shootings; accordingly, our main estimates likely represent the causal effect of exposure to mass shooting incidents and are not due to pre-existing differential trends between county residents who were interviewed before versus after the shooting. Our findings suggest that mass shootings have significant societal costs and create negative spillover effects that extend beyond those immediately exposed.