How Do Close-Circuit Television Cameras Impact Crimes and Clearances?: An evaluation of the Milwaukee police department’s public surveillance system

This study uses quasi-experimental analyses to estimate the effectiveness of police-operated CCTV cameras in Milwaukee, Wisconsin. Most studies have focused on how cameras can deter crime. But, like many other agencies, the Milwaukee Police Department strategically deployed their cameras in high-crime, high-traffic intersections to aid criminal investigations. Thus, this study examines the impact of CCTV cameras on crimes and crime clearances. We also examine the differential impacts of CCTV in three treatment groups: all intersections that received a new camera, intersections where new cameras were installed alongside existing cameras, and intersections where only new cameras were installed. We used propensity score matching to create comparison groups of camera-free intersections, then employed difference-in-differences estimation with negative binomial and Poisson panel regression models to determine whether CCTV cameras have an impact on various categories of crimes and clearances. Despite overall crime declines in Milwaukee during the study period, we found that treatment intersections experienced more crimes post-intervention than comparison areas, likely because camera operators were using them to detect incidents that would have otherwise gone unreported. We also found limited evidence that CCTV cameras improve clearances.