The Urban Institute just released a study of surveillance systems in three cities, Baltimore, Maryland; Chicago, Illinois; and Washington, D.C., to document how they were being used and analyze how much they were affecting crime, if at all. The theory is that surveillance cameras will deter potential offenders, alert police to dangerous situations, generate evidence to help identify suspects and witnesses, and foster the perception of safety, encouraging people to use public spaces. The group evaluated each city system to learn whether it was effective and cost-beneficial and drew on the site experiences to offer lessons to other jurisdictions. Results varied, with crime falling in some areas and remaining unchanged in others. Much of the success or failure depended on how the surveillance system was set up and monitored and how each city balanced privacy and security. Baltimore virtually saturated its downtown area with cameras and assigned police to monitor live video feeds around the clock. Chicago installed an extensive wireless network of cameras and allowed access to all officers. Washington, having the fewest cameras of the three sites, placed them strategically in high-crime areas. The site also restricted live monitoring to protect the privacy of people being recorded. More details at