Can Enhanced Street Lighting Improve Public Safety at Scale?

Research Summary: Street crimes are thought to be influenced by changes in ambient lighting, yet most studies have focused on small-scale interventions in limited areas. It remains unclear whether enhanced lighting can improve safety on a larger, jurisdiction-wide scale. This study examined the first 10 months of Philadelphia's citywide rollout of enhanced street lighting. Between August 2023 and May 2024, 34,374 streetlights were upgraded across 13,275 street segments, converting roughly one-third of the city's street segments to new LED (light-emitting diode) fixtures that provide clearer and more even lighting. We assessed the impact of these upgrades on total crimes, violent crimes, property crimes, and nuisance crimes. Our findings reveal a 15% decline in outdoor nighttime street crimes and a 21% reduction in outdoor nighttime gun violence following the streetlight upgrades. The streetlight upgrades may have contributed to 5% of the citywide decline in Philadelphia gun violence during the study period. Qualitative data also suggests that resident perceptions of safety and neighborhood vitality improved after new streetlights were installed. Policy Implications: While prior research has mostly focused on small-scale implementations, our study demonstrates that improvements in street lighting can significantly reduce crime rates across large urban areas. These results support the adoption of energy-efficient LED street lighting as a crime reduction strategy for cities. Further research is needed to explore the impact of enhanced streetlight interventions on other types of crime and to determine whether the crime-reduction benefits are sustained when these upgrades are implemented across the entire City of Philadelphia for extended periods.