While the migration of Abraham Lincoln’s family to the Northwest has often been documented as a significant event of his youth, historians have neglected the powerful repercussions this family decision had on Lincoln’s assessment of the South and the secession crisis in 1860 and 1861. Lincoln’s years living and working in the Northwest from 1831 to 1861 exposed him to the anti–slave system ethos of that region’s southern-born migrants. Sensitive to the restraints they believed the social system of slavery placed upon their own liberties, these former southerners simultaneously despised the slave system, hated African Americans, and sympathized with white slaveholders and nonslaveholders who remained in the South. After building his initial sense of southern society from these migrants, Lincoln spent his years as a U.S. congressman learning the significance of the Northwest Ordinance in creating the free society in which they had thrived. Emphasizing Thomas Jefferson’s role in conceiving the Northwest Ordinance and utilizing statistical evidence to prove the superiority of free soil over slave, Lincoln’s colleagues further expanded Lincoln’s conception of the South. All these influences combined to produce Lincoln’s uniquely northwestern approach to slavery, the South, and the secession crisis. Believing that the self-interest of white nonslaveholding southerners naturally propelled them away from the South and toward free society, Lincoln perceived the slave South as a vastly unequal society controlled by a minority of aristocratic slaveholders who cajoled or chided their nonslaveholding neighbors into accepting a vision of the South’s proslavery, expansionist future. As president-elect, Lincoln therefore overestimated the Unionist sentiment of southerners before and during the secession crisis. He remained convinced that the majority of white nonslaveholders would not support a secessionist movement that he believed countered their own self-interest. With time, and through careful communications with the South, he remained convinced that he could settle secessionist passions and bring southerners to trust him and the Republican Party. This northwestern perception of the South therefore explains, in part, Lincoln’s silence and his refusal to compromise during the secession crisis.