Despite the United States' ban on slave importation in 1808, profitable interstate slave trading continued. The nineteenth century's great cotton boom required vast human labor to bring new lands under cultivation, and many thousands of slaves were torn from their families and sold across state lines in distant markets. Shocked by the cruelty and extent of this practice, abolitionists called upon the federal government to exercise its constitutional authority over interstate commerce and outlaw the interstate selling of slaves. This groundbreaking book is the first to tell the complex story of the decades-long debate and legal battle over federal regulation of the slave trade. David Lightner explores a wide range of constitutional, social, and political issues that absorbed antebellum America. He revises accepted interpretations of various historical figures, including James Madison, Harriet Beecher Stowe, and Abraham Lincoln, and he argues convincingly that southern anxiety over the threat to the interstate slave trade was a key precipitant to the secession of the South and the Civil War.