Abstract
IMPORTANCE: Black and other racially minoritized groups are overrepresented among those who experience firearm homicide. There has been a stark increase in incarcerated populations in the US since the 1980s, largely due to differential drug sentencing, of which racially minoritized individuals are also overrepresented; social disorganization theory postulates that community and family instability resulting from incarceration can further worsen crime. OBJECTIVE: To understand the association of race-specific incarceration with race-specific firearm violence rates in Chicago, Illinois, through the lens of social vulnerability and family instability. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study with a retrospective cohort design utilized homicide data for the city of Chicago from January 1, 2001, to August 31, 2019. Demographic data at the census block level was obtained from the 2010 decennial census. Incarceration rates were obtained by race and ethnicity at the census tract level from the Opportunity Atlas. Data analysis occurred from January to June 2023. EXPOSURE: Race-specific incarceration rates were the primary exposures of interest. The Social Vulnerability Index and single-parent households were studied as mediators. MAIN OUTCOMES AND MEASURES: Race-specific firearm homicide rates were the outcomes of interest. Structural equation modeling was used to understand the mediating effect of social vulnerability and single-parent households on the association of incarceration with firearm homicides. RESULTS: A total of 46 312 census blocks were evaluated. Black-specific incarceration rates were found to be associated with Black-specific firearm homicides (incidence rate ratio [IRR], 1.70; 95% CI, 1.50-1.94), but there was no association for Hispanic incarceration rates (IRR, 0.98; 95% CI, 0.75-1.28) or White incarceration rates (IRR, 1.13; 95% CI, 0.39-1.16). In the association of Black incarceration rates with Black firearm homicide rates, social vulnerability did not mediate the interaction, but the percentage of single-parent households mediated 23% of the interaction. CONCLUSIONS AND RELEVANCE: This study found that higher rates of incarceration were associated with increased rates of firearm homicides among Black communities alone; this association was found to be mediated partially through the density of single-parent households in these areas, suggesting that social disorganization resulting from mass incarceration may perpetuate firearm homicides. Targeted policies addressing mass incarceration and the disparities therein may be a means of reducing urban firearm homicides.