Among the most striking examples of mass civil disobedience ever to occur in the United States, the Underground Railroad occupies a significant place in American history. Although African American slaves were denied the legal protections of citizenship and their owners' rights to recapture runaways were decreed by federal statute, countless citizens defied the law to assist fugitives to freedom, and even more slaves escaped abetted only by their own initiative and desire for liberty. While firm numbers are difficult to establish due to the Underground Railroad's necessary secrecy, it is believed that between the late eighteenth century and the outbreak of the Civil War in 1861, more than fifty thousand slaves successfully escaped bondage. Their destinations were almost as various as the railroad's routes that snaked unmarked throughout the slave states. Many fugitives fled to the Northern states, but thousands...