Homelessness in America has grown from a minor problem in isolated areas of a few big cities into a near epidemic. Today, scarcely any American city of any appreciable size lacks homeless people. Homeless shelters and programs have become as essential and as commonplace as police protection or water and sewage treatment. What to do for, with, or about the homeless is a nagging and complex social policy issue debated at all levels of government.

Address Unknown emphasizes the large-scale social and economic forces that have priced an increasingly large segment of the urban...