Association Between Markers of Structural Racism and Mass Shooting Events in Major US Cities

IMPORTANCE: The root cause of mass shooting events (MSEs) and the populations most affected by them are poorly understood. OBJECTIVE: To examine the association between structural racism and mass shootings in major metropolitan cities in the United States. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study of MSEs in the 51 largest metropolitan statistical areas (MSAs) in the United States analyzes population-based data from 2015 to 2019 and the Gun Violence Archive. The data analysis was performed from February 2021 to January 2022. EXPOSURE: Shooting event where 4 or more people not including the shooter were injured or killed. MAIN OUTCOME AND MEASURES: MSE incidence and markers of structural racism from demographic data, Gini income coefficient, Black-White segregation index, and violent crime rate. RESULTS: There were 865 MSEs across all 51 MSAs from 2015 to 2019 with a total of 3968 injuries and 828 fatalities. Higher segregation index (ρ = 0.46, P = .003) was associated with MSE incidence (adjusted per 100 000 population) using Spearman ρ analysis. Percentage of the MSA population comprising Black individuals (ρ = 0.76, P < .001), children in a single-parent household (ρ = 0.44, P < .001), and violent crime rate (ρ = 0.34, P = .03) were other variables associated with MSEs. On linear regression, structural racism, as measured by percentage of the MSA population comprising Black individuals, was associated with MSEs (β = 0.10; 95% CI, 0.05 to 0.14; P < .001). Segregation index (β = 0.02, 95% CI, −0.03 to 0.06; P = .53), children in a single-parent household (β = −0.04, 95% CI, −0.11 to 0.04; P = .28), and Gini income coefficient (β = −1.02; 95% CI, −11.97 to 9.93; P = .93) were not associated with MSEs on linear regression. CONCLUSIONS AND RELEVANCE: This study found that major US cities with higher populations of Black individuals are more likely to be affected by MSEs, suggesting that structural racism may have a role in their incidence. Public health initiatives aiming to prevent MSEs should target factors associated with structural racism to address gun violence.