Gun Dealer Density and Its Effect on Homicide

We explore the relationship between gun prevalence and homicides in the United States in 2003-19. We create a novel measure of gun density in a narrow geographic area using an underutilized metric: gun dealers. We find that an increase in gun dealer density is significantly and positively associated with increased homicides in subsequent years. We compare estimates from our preferred measure to those found using other gun prevalence measures. We show that the effect of gun dealer density is limited mostly to counties with a high percentage of Black residents and metropolitan areas. We propose that the so-called Ferguson effect-a sharp increase in violent crime in urban and Black communities after 2014-might be largely explained by an influx of gun dealers in and near Black communities rather than a change in the propensity of Black residents to call the police or changes in policing.