May 1854

Senator Stephen Douglas's Kansas-Nebraska Act, signed May 30, 1854, repeals the Missouri Compromise's prohibition of slavery north of 36°30' and replaces it with "popular sovereignty." The act shocks the North, destroys the Whig Party, triggers the founding of the Republican Party, and launches Bleeding Kansas — a guerrilla war over whether Kansas would be slave or free.

Senator Stephen Douglas's Kansas-Nebraska Act repealed the Missouri Compromise of 1820 and replaced it with 'popular sovereignty' — settlers in each territory would vote on slavery. This opened Kansas and Nebraska territories, previously designated free, to potential slavery. The law shattered the Whig Party, created the Republican Party, and triggered a guerrilla war in Kansas. Pro-slavery forces from Missouri ('Border Ruffians') flooded Kansas to stuff ballot boxes, establishing a fraudulent pro-slavery territorial government. Anti-slavery settlers established a rival government. The result was years of violent conflict.