Often described as an emergency, homelessness in America is becoming a chronic condition that reflects an overall decline in the nation's standard of living and the general state of the economy. This is the disturbing conclusion drawn by Martha Burt in Over the Edge, a timely book that takes a clear-eyed look at the astonishing surge in the homeless population during the 1980s. Assembling and analyzing data from 147 U.S. cities, Burt documents the...