Kathy Van Sluyters (left), Barbara Carr and Colleen Dickinson chat on a recently finished sidewalk across from Wildflower Terrace, a mixed-income apartment building in the Mueller development for people ages 55 and over. Julia Robinson for NPR hide caption

itoggle caption Julia Robinson for NPR

On a corner in Washington, D.C., where stores burned during riots 44 years ago, there's now a plaza where farmers sell produce on Saturday mornings. Dan Charles/NPR hide caption

itoggle caption Dan Charles/NPR