According to a study conducted by the University of Pennsylvania’s Wharton School of Business, trees planted within fifty feet of houses in one Philadelphia neighborhood caused home prices to increase by 9 percent.20 A more comprehensive study, this time of Portland’s east side, reached conclusions that were less dramatic but, taken as a whole, no less compelling. Comparing houses with and without nearby street trees, it found that an adjacent tree added 3 percent to the median sale price of a house,
