11. The Kansas-Nebraska Act (1854)
The Kansas-Nebraska Act of 1854, introduced by Senator Stephen A. Douglas, established the territories of Kansas and Nebraska and allowed settlers to decide on the legality of slavery through popular sovereignty. This effectively repealed the Missouri Compromise, which had prohibited slavery in these regions. The act led to violent conflicts between pro-slavery and anti-slavery factions, known as “Bleeding Kansas,” as both sides rushed to influence the outcome (kansashistory.gov).
