Kansas-Nebraska Act

critical national policy change concerning the expansion of slavery into the territories, affirming the concept of popular sovereignty over congressional edict. In 1820 the Missouri Compromise had excluded slavery from that part of the Louisiana Purchase (except Missouri) north of the 36°30′ parallel. The Kansas-Nebraska Act, sponsored by Democratic Senator Stephen A. Douglas, provided for the territorial organization of Kansas and Nebraska under the principle of popular sovereignty, which had been applied to New Mexico and Utah in the Compromise of 1850. Passage of the Act was followed by the establishment of the Republican Party as a viable political organization opposed to the expansion of slavery into the territories.