After decades of urban depopulation, US cities are experiencing a reversing of that trend, led by millennials, 40 percent of whom say they plan to live their lives in urban settings. But families and empty nesters are moving to the city too, and for the first time since the 1920s, population growth in US cities is outpacing the growth of the suburbs. What will this reshaping of the American landscape mean for society? How will cities grow and change to accommodate new populations, a changing environment, and a global economy? What will drive innovation and economic growth in the new urban context? And how can cities best plan, govern, and design for the future?