The Association Between Vacant Lot Redevelopment and Violent/Firearm Violent Crime: A Difference-in-Difference Analysis From 2007 to 2023

Objectives. To investigate the association between vacant lot redevelopment and violent crime and firearm violent crime. Methods. We used a quasi-experimental study with a difference-in-difference (DID) design. The study population was 254 vacant lots located in Philadelphia, Pennsylvania. The exposure was redevelopment, defined as repurposing the vacant lot into a permanent structure (e.g., housing) between 2007 and 2023. The outcome was violent crime subtypes and firearm violent crime subtypes reported to the police. Our primary analysis used a staggered DID estimator. Results. We found a negative association between redevelopment and aggravated assault (DID = −56.55 crimes per square mile per year; 95% confidence interval CI = −97.86, −15.24), firearm aggravated assault (DID = −35.11 crimes per square mile per year; 95% CI = −55.41, −14.82), and overall firearm violent crime (DID = −27.26 crimes per square mile per year; 95% CI = −52.97, −1.54). We did not find significant associations for the other outcomes tested. Conclusions. Our results support the hypothesis that vacant lot redevelopment may prevent or displace violent crime. Public Health Implications. Built environment investments may prevent or displace violence. ( Am J Public Health. 2026;116(1):95–102. https://doi.org/10.2105/AJPH.2025.308269 )