The Kansas-Nebraska Act of 1854 was, as Brown explains here, “almost certainly the most lethal piece of legislation to ever clear Congress.” In reversing the Missouri Compromise of 1820 and allowing slavery to expand into vast new western territories, the act deepened divisions between North and South and pushed the country toward civil war. This engaging history first examines the precarious balance struck between sectional differences at the nation’s founding, then charts its dramatic demolition in the mid-19th century. Brown offers revealing studies of central figures in this historical period, from politicians Stephen A. Douglas and Abraham Lincoln, to authors and social commentators Harriet Beecher Stowe and Ralph Waldo Emerson, to abolitionist activists Harriet Tubman and Frederick Douglass. Particularly rewarding are the author’s analyses of Stowe’s Uncle Tom’s Cabin and its indictment of “those various northern networks of complicity—merchants and insurers, lawyers and creditors—that [kept] the business of bondage strong, expansive, and legal.” Emerson’s complex attitudes about racial differences are also given sensitive and revealing consideration: “Unable to grieve for a race he did not know, Emerson ultimately entered the public outcry against slavery when he recognized the institution as an infringement of white freedom.” Another intriguing and persuasive feature of this book’s commentary is its suggestion that the polarized conditions of antebellum America parallel those of the contemporary moment. Brown’s ultimate conclusions are apt, compelling, and memorably expressed: “Ill served were the youth who came of age when a divided Congress passed the Kansas-Nebraska Act, in whose wake came a great reckoning, the measured resonance of an original sin that had long shaken the country—and stirs through it still.”