The enduring impact of historical and structural racism on urban violence in Philadelphia.

Public health approaches to crime and injury prevention are increasingly focused on the physical places and environments where violence is concentrated. In this study, our aim is to explore the association between historic place-based racial discrimination captured in the 1937 Home Owners Loan Corporation (HOLC) map of Philadelphia and present-day violent crime and firearm injuries. The creators of the 1937 HOLC map zoned Philadelphia based in a hierarchical system wherein first-grade and green color zones were used to indicate areas desirable for government-backed mortgage lending and economic development, a second-grade or blue zone for areas that were already developed and stable, a third-grade or yellow zone for areas with evidence of decline and influx of a "low grade population," and fourth-grade or red zone for areas with dilapidated or informal housing and an "undesirable population" of predominately Black residents. We conducted an empirical spatial analysis of the concentration of firearm assaults and violent crimes in 2013 through 2014 relative to zoning in the 1937 HOLC map. After adjusting for socio-demographic factors at the time the map was created from the 1940 Census, firearm injury rates are highest in historically red-zoned areas of Philadelphia. The relationship between HOLC map zones and general violent crime is not supported after adjusting for historical Census data. This analysis extends historic perspective to the relationship between emplaced structural racism and violence, and situates the socio-ecological context in which people live at the forefront of this association.