Neighborhoods with homes fronted with street trees experience lower crime rates, according to a study conducted in Portland, Oregon. The same statistic holds true for homes with large yard trees. These results hold for total-crime rates as well as specific property crimes such as vandalism and burglary.
Trees may reduce crime by signaling that a neighborhood is well cared for. These findings are consistent with the “broken window” hypothesis, which maintains that signs of neighborhood neglect, such as graffiti or untended yards, send a signal to potential criminals that residents may not take steps to protect their neighborhood.