Abstract
This study explores whether population-level measures of income inequality and poverty rates are associated with mass shootings in the United States. We test these potential connections by examining the incidence rate of mass shootings using random effects negative binomial regressions for a panel data-set that included 3144 counties for the years 1990-2015. According to the adjusted models, income inequality is significantly associated with the three or more victim-related injuries (incidence rate ratio [IRR] = 1.39; 95% confidence interval [CI] = 1.11, 1.67; P < .001) and four or more victim-related deaths definition of mass shootings (IRR = 1.36; 95% CI = 1.08, 1.64; P < .01). However, poverty rates lack a reliable association with the three or more injuries (IRR = 1.07; 95% CI = .75, 1.39) and four or more deaths definition (IRR = .95; 95% CI = .71, 1.19). When considered in conjunction with the literature on inequality and crime, these results indicate that counties with high inequality may foster an environment of anger and resentment that ultimately leads to mass shootings.