"After the Civil War and throughout the twentieth century, cities in northern American states absorbed a huge increase in populations, particularly of immigrants and African Americans from southern states. City governments responded by creating new regulations that were often segregationist -- corralling black Americans, for example, into small, increasingly overcrowded neighborhoods, or into high-rise "projects." The situation intensified after World War II, as rising crime and racial unrest swept the nation, and blame fell on the crowded conditions of city life. The hardest-hit populations were left marginalized and voiceless. Enter John B. Calhoun, an ecologist employed by the National Institute of Mental Health to study the effects of overcrowding on rats. From 1947 to 1977, Calhoun built a series of sprawling habitats in which a rat's every need was met--except space. The results were cataclysmic. Did a similar fate await our own teeming cities?" -- Provided by publisher.