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How do close-circuit television cameras impact crimes and clearances? An evaluation of the Milwaukee police department's public surveillance system

NCJ Number
Police Practice and Research Dated: 2020
Date Published

This study used quasi-experimental analyses to estimate the effectiveness of police-operated closed-circuit television (CCTV) cameras in Milwaukee, Wisconsin.


Most studies of the public-safety use of CCTVs in public place have focused on how cameras can deter crime. 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 examined the impact of CCTV cameras on crimes and crime clearances. It also examined 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. Propensity score matching was used to create comparison groups of camera-free intersections, followed by the use of difference-in-differences estimation with negative binomial and Poisson panel regression models to determine whether CCTV cameras have had an impact on various categories of crimes and clearances. Despite overall crime declines in Milwaukee during the study period, the current study 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. This evaluation also found limited evidence that CCTV cameras improved clearances for crimes committed in areas where CCTV was deployed.

Date Published: January 1, 2020