• The authors would like to thank Philadelphia Police Commissioner Charles Ramsey and the executive team at the Philadelphia Police Department for their collaborative approach to research and their support of this project, including Deputy Commissioner Richard Ross, Deputy Commissioner Tommy Wright, Deputy Commissioner Kevin Bethel, Chief Administrative Officer Nola Joyce, and Director of Strategic Communications Karima Zedan. We also would like to show our appreciation to the district commanders and patrol officers for their hospitality. The authors would like to thank Evan Sorg, Lallen Johnson, and Cory Haberman for their assistance with fieldwork, and John Goldkamp, Ralph B. Taylor, and the anonymous reviewers for their insightful comments on various drafts of this article. Aspects of this research were funded through the Robert Wood Johnson Foundation's national program for Public Health Law Research, and the Temple University College of Liberal Arts Research Award (CLARA) Program. The points of view or opinions expressed herein are those of the authors and do not necessarily represent the official position of the Philadelphia Police Department or the City of Philadelphia. Direct correspondence to Jerry H. Ratcliffe, Department of Criminal Justice, Temple University, 1115 Polett Walk, Philadelphia, PA 19122 (e-mail:


Originating with the Newark, NJ, foot patrol experiment, research has found police foot patrols improve community perception of the police and reduce fear of crime, but they are generally unable to reduce the incidence of crime. Previous tests of foot patrol have, however, suffered from statistical and measurement issues and have not fully explored the potential dynamics of deterrence within microspatial settings. In this article, we report on the efforts of more than 200 foot patrol officers during the summer of 2009 in Philadelphia. Geographic information systems (GIS) analysis was the basis for a randomized controlled trial of police effectiveness across 60 violent crime hotspots. The results identified a significant reduction in the level of treatment area violent crime after 12 weeks. A linear regression model with separate slopes fitted for treatment and control groups clarified the relationship even more. Even after accounting for natural regression to the mean, target areas in the top 40 percent on pretreatment violent crime counts had significantly less violent crime during the operational period. Target areas outperformed the control sites by 23 percent, resulting in a total net effect (once displacement was considered) of 53 violent crimes prevented. The results suggest that targeted foot patrols in violent crime hotspots can significantly reduce violent crime levels as long as a threshold level of violence exists initially. The findings contribute to a growing body of evidence on the contribution of hotspots and place-based policing to the reduction of crime, and especially violent crime, which is a significant public health threat in the United States. We suggest that intensive foot patrol efforts in violent hotspots may achieve deterrence at a microspatial level, primarily by increasing the certainty of disruption, apprehension, and arrest. The theoretical and practical implications for violence reduction are discussed.