In recent months America’s affordable housing crisis, a long-simmering issue for people of low and moderate incomes, has burst onto the front page. Rents are rising much faster than income, while the median home price in some 200 cities is $1 million. After a decade of decline, the number of homeless Americans is ticking back up. The private market is clearly failing. Although many city and state governments are motivated to take action, they have limited tools at their disposal, and few of them equal to the task. The Department of Housing and Urban Development, at least under its current leadership, is hardly stepping up.