As the appetite for urban living in the U.S. increases, cities are facing a need for housing not seen in decades. In this special report, we look at three metropolitan areas working to accommodate growing populations. In Boston, as people follow the tech sector and other enterprises into the urban core, the city is reinventing its historic neighborhoods and creating new ones. Portland, Oregon, is racing to keep up with an influx of newcomers seeking the much-hyped quirkiness that the city has embraced as a brand. In the wake of Hurricane Katrina, New Orleans has emerged as a hub for new industries—from technology to film—attracting a population enchanted by its unique history and culture. Despite high demand pushing up housing costs, all three cities are struggling to maintain economically diverse communities—an essential ingredient of a thriving urban center.