This is a tale of two (kinds of) cities. First, there are the fast-growing coastal megalopolises—including Washington, DC, Seattle, and San Francisco—where an influx of millennials has spurred new investment in housing, transit, parks and other amenities. In those cities, the much celebrated urban revitalization has come at a cost: it has displaced countless long-time residents—especially people of color and those of limited means—who can no longer afford their newly gentrified neighborhoods.