Did community greening reduce crime? Evidence from Hew Haven, CT, 1996-2007
Community greening did not show a reduction in crime in New Haven, CT
The purpose of this study was to determine if community greening over more than a decade had an effect on crime levels at planting sites in New Haven, CT. Community greening is a bottom-up versus top-down approach to urban greening. With community-greening, volunteers rather than government agencies set the goals and determine the activities of tree planting and other urban greening initiatives. Volunteers are sometimes motivated to work on community-greening projects to reduce crime and make their cities safer. While previous studies suggest that less crimes occur in neighborhoods with more trees, they did not specifically address community-based tree planting and crime. This quasi-experimental study was designed to fill this gap.
The crime rates of 300 community-led intervention sites (tree-planting sites) were compared to the crime rates of 893 control sites (sites without community-led interventions, matched on a variety of factors) over a twelve-year period. The data was based on individual street segments consisting of properties on both sides of the street bounded by the two closest cross streets. This type of spatial unit is referred to as a block face. Trees planted on the intervention sites included both street trees and trees in community gardens and parks. Data on the trees included the year of planting. Data analysis considered violent, property, and misdemeanor crimes individually and jointly to test for crime-type specific effects. The analysis controlled for sociodemographic factors and both space- and time-related trends.
Findings indicated that the crime rates on the community greening sites were not significantly different than the crime rates on the control sites. The researchers offer several possible explanations as to why these findings are not consistent with previous studies on the relationship between neighborhood greening and crime. One suggestion is that there may have been spillover from the intervention to the control sites.
The researchers discuss future research implications relating to tree inventories and monitoring, study design, and techniques to assess impacts of tree planting efforts. They conclude their report by noting that, while this study did not indicate that community greening was associated with a reduction in crime, “the process of tree planting and the resulting street trees provide many other social and environmental benefits.”
Citation
Locke, D.H., Han, S.H., Kondo, M.C., Murphy-Dunning, C., Cox, M., (2017). Did community greening reduce crime? Evidence from Hew Haven, CT, 1996-2007. Landscape and Urban Planning, 161,
