How and why did decades of arguing over the future of slavery in the United States culminate in America’s deadliest war? We will investigate polarizing political controversies, cultural developments, social trends, and military conflicts between 1820 and 1860 and ask how Americans in both the North and South came to believe that their countrymen belonged to a hostile, foreign culture. Other major themes will include the role of American exceptionalism, the broad spectrum of anti-slavery sentiment, and evolving rhetorical defenses of slavery.