A new study finds that each dollar spent repairing abandoned buildings and vacant lots reduces neighborhood gun violence and yields, respectively, a $5 and $26 return on investment (ROI) to taxpayers, and a $79 and $333 ROI to society at large through steps like installing working doors and windows in abandoned buildings, as well as removing trash and debris, and planting grass and trees.

The study, published today in the American Journal of Public Health by researchers at the Perelman School of Medicine and the Wharton School at the University of Pennsylvania, is the first to report the cost-benefit and percentage reduction estimates for urban blight and firearm violence.

Gun violence in the U.S. is higher than in any other developed nation, and the majority of fatal violence  involves firearms. Every year about 100,000 people are shot in the U.S., according to the Centers for Disease Control.

“The immeasurable pain and void left when lives are lost to firearm violence sends a ripple effect through families and neighborhoods,” said the study’s lead author Charles C. Branas,  a professor of Epidemiology and director of the Penn Urban Health Lab. “This study demonstrates sustainable, replicable strategies that successfully reduce firearm violence. They can transform communities across the country, save lives, and provide well more than a full return on investment to tax payers and their communities.”

Studying over 5,000 abandoned buildings and vacant lots, and their impact on firearm and nonfirearm violence in Philadelphia, the team found that firearm violence decreased 39 percent in and around areas where doors and windows were restored on abandoned buildings, and decreased 5 percent in and around vacant lots that had been well maintained – decreases sustained up to nearly four years after the intervention. Neither revitalization method significantly affected nonfirearm violence rates, however, pointing to the distinct impact that blight remediation efforts can have on the misuse of illegal firearms in challenged urban communities.

Comparing rehabbed, previously abandoned buildings, to a randomly selected, matched group of abandoned buildings that had not been treated, as well as remediated vacant lots with blighted lots, the team recorded Philadelphia Police Department firearm violence statistics monthly for both groups.

The authors note that future trials and studies in other cities would be valuable in further demonstrating replicability and reveal insights into the types of neighborhoods and implementation methods that can yield the best reductions in firearm violence.