The Economic Impact of Greening Urban Vacant Land: A Spatial Difference-In-Differences Analysis

Abstract

Vacant land is a serious problem in many cities, and cities have recently begun to explore greening as a management strategy to reduce the negative influence of vacancy. The city of Philadelphia, Pennsylvania pioneered the use of a simple greening treatment—removal of debris coupled with planting grass and trees—as a means of improving blighted communities. Though they are becoming more popular, the actual economic impact of these programs is not well understood. This paper details the use of a spatial difference-in-differences approach for measuring the impact of Philadelphia's innovative vacant land greening program on nearby residential property values. This approach compares observed changes in property values surrounding treated vacant lots with observed changes around control lots—lots which might have been treated but were not. While property values throughout the city increased during the study period, properties surrounding greened vacant lots had a greater increase in value than properties surrounding nongreened vacant lots. By developing both global and local versions of the model, we also explore spatial variation in the impacts of the program—offering insight into which kinds of neighborhoods might derive the greatest economic benefit from vacant land greening programs.