Stephen A. Douglas rose in Illinois politics after working as a teacher and lawyer. He held offices including secretary of state and justice of the Illinois Supreme Court before entering the United States House in 1843. Elected to the Senate in 1847, he became a leading Democrat and an influential advocate of western development. His national prominence rested on legislative skill and the belief that territorial questions could be managed through local political decisions rather than permanent federal restrictions.

Douglas helped organize passage of the separate measures forming the Compromise of 1850. He then sponsored the Kansas-Nebraska Act of 1854, which created new territories and allowed their settlers to decide whether to permit slavery through popular sovereignty. The law effectively repealed the Missouri Compromise restriction and intensified sectional conflict. Competing proslavery and antislavery efforts in Kansas produced violence and undermined his claim that local decision-making would settle the issue peacefully.

In 1857 Douglas opposed the proslavery Lecompton Constitution for Kansas because he considered it unrepresentative of the settlers' wishes. This position divided him from President James Buchanan and southern Democrats. During the 1858 Illinois Senate campaign he debated Abraham Lincoln in a series of public encounters centered on slavery and the Union. At Freeport he argued that local authorities could prevent slavery through the absence of supporting legislation despite the Supreme Court's Dred Scott decision. He retained his Senate seat through legislative election, but the position further damaged his standing among southern allies.

The Democratic Party split in 1860, and Douglas ran for president as the nominee of its northern wing. Lincoln won the election, while Douglas received a substantial national popular vote but few electoral votes. After secession and the outbreak of war, Douglas urged Democrats to support the Union and Lincoln's government. He died in June 1861. His career illustrates both the possibilities of compromise legislation and its limits when the underlying question involved human bondage. Popular sovereignty treated white settlers as the decision-makers while excluding enslaved people's rights from the process. His determination to preserve the Union was real, but the territorial policy most associated with him helped accelerate the political crisis he sought to contain.