This volume of primary documents on the causes of the Civil War presents the history of the American political order during its most tumultuous and challenging time. More than a century and a half after the crisis came to an end, Americans remain fascinated by it, as they should be. The Civil War is the defining event in American political development. It put to the test whether the “one people,” as Thomas Jefferson wrote in the Declaration of Independence, would remain one. The documents selected for inclusion in this volume range from a little-known 1819 Congressional speech by James Tallmadge Jr. on the future status of slavery in the territories to Abraham Lincoln’s widely read First Inaugural Address (1861), in which he tried to prevent civil war as Southern states seceded. In between, the reader will discover the central political, constitutional, moral, social, and economic themes that shaped the nation’s history during its most critical period, as told by those who lived through it. The documents trace these themes, from both the Northern and Southern points of view. In their famous debate in 1830, Senators Daniel Webster (Massachusetts) and Robert Y. Hayne (South Carolina) argued over two radically different understandings of the origin and nature of the American Union and the legality of secession (Webster-Hayne Debates (1830)). William Lloyd Garrison (On the Constitution and the Union (1832)), John C. Calhoun (Speech on Abolition Petitions (1837)), and Abraham Lincoln (Fragment on the Constitution and the Union (1861)) discussed the proper relationship between the Constitution and the Union, and its effect on understanding secession and the dissolution of the government. George Fitzhugh (Sociology for the South (1854)) and James Henry Hammond (“Mud Sill” Speech (1858)) argued that the slave system of the South was superior to the free labor system of the North, while William H. Seward (“An Irrepressible Conflict” (1858)) and Abraham Lincoln (Address Before the Wisconsin State Agricultural Society (1859)) defended free labor. Speeches and resolutions before Congress (Speech to Congress (1819); Missouri Compromise Act (1820); Webster-Hayne Debates (1830); Speech on Abolition Petitions (1837); Speech on the Oregon Bill (1848); The Compromise of 1850 (1850); Appeal of the Independent Democrats (1854); “Nebraska Territory” (1854); “Mud Sill” Speech (1858)); interpretations of executive power by Abraham Lincoln (First Inaugural Address (1861)); and arguments in the Dred Scott Supreme Court case (Dred Scott v. Sandford (1857); Reply to the Dred Scott Decision (1857)) addressed the use and abuse of the legitimate powers under the Constitution of the three branches of government. Finally, and most important, Lincoln and Stephen A. Douglas argued over the limits of popular sovereignty, and thus over the connection between the Declaration of Independence and the Constitution (Reply to the Dred Scott Decision (1857); “Homecoming” Speech (1858); Fragment on the Constitution and Union (1861)). Despite these different perspectives, however, all of the documents in this collection revolve around one central idea that is at the heart of any attempt to understand the coming of the Civil War: slavery, or, perhaps more rightly, the extension of slavery into the territories. From out of the territories new states came into the Union, and with them the power either to protect or to destroy slavery forever by Constitutional amendment, depending on whether proslavery or antislavery forces dominated in the Congress and in the state legislatures. It was in the territories, therefore, that everyone at the time understood that the future of slavery, and with it, the future of the nation, would be decided. No one can read these documents today without sensing the overwhelming significance the debate over slavery had in the minds of the people of that era, as it was the only serious issue that threatened to divide them and destroy their political existence. South Carolina’s Declaration of the Causes of Secession (South Carolina’s Declaration of the Causes of Secession (1860)), like similar reports issued by every state that eventually left the Union, identified the protection of slavery as the primary justification for secession. From all points of view and all walks of life, the core argument always came back to slavery in one way or another, as these documents illustrate. From these documents, the reader can come to understand and appreciate not only the history of the United States during the Civil War era, but also something about the challenges we have faced and the progress we have made as “one people.” If we are to remain one and dedicated to our defining proposition—that all are created equal—every generation of Americans must understand the time and the reasons why we almost ceased to be.