At first glance, the numbers released by the Census Bureau last week showing a precipitous drop in Detroit’s population — 25 percent over the last decade — seem to bear a silver lining: most of those leaving the city are blacks headed to the suburbs, once the refuge of mid-century white flight. But a closer analysis of the data suggests that the story of housing discrimination that has dominated American urban life since the early 20th century is far from over. Detroit is not the only American city to face persistent residential segregation, but it is among the worst: it...