One of the most divisive pieces of legislation in American history, the Kansas-Nebraska Act significantly heightened the growing sectional conflict of the 1850s and effectively destroyed the Whig Party. Having established the principle of "popular sovereignty" as the vehicle for establishing the slave status of the southwestern territories in the Compromise of 1850, the Democratic Party sought an opportunity to extend that policy into the rest of the American West. In 1854, the Senate Committee on the Territories, headed by Stephen A. Douglas, proposed creation of two new territories, Kansas and Nebraska, and declared the territories' slave status would be determined through popular sovereignty. This effectively revoked the Missouri Compromise but Douglas believed it would ultimately solve the sectional crisis by unifying the nation behind the concept of popular sovereignty and in the establishment of a continental railroad that would go through the new territories. The bill passed the Senate by a large majority but passed the House of Representatives by only thirteen votes. Franklin Pierce signed it into law on May 30. The failure of Douglas's vision became immediately apparent, as violence and corruption dominated the Kansas Territory's slavery vote and resulted in a period of extended conflict in that area, known generally as Bleeding Kansas. Support for the act also permanently destroyed the already-fragile second party system by forcing politicians to favor sectional interests over party loyalty. The Democrats were able to survive the crisis but became increasingly divided between northern and southern members. The Whigs, on the other hand, split geographically and ceased to be a national party. The Kansas-Nebraska Act is also noteworthy for motivating Abraham Lincoln to return to politics after a period of disaffection and eventually join the Republican Party. The Republicans were, in part, founded specifically to oppose the act.
“An Act to Organize the Territories of Kansas and Nebraska,” 30 May 1854, Statutes at Large of the United States 10 (1855):277-90; Michael A. Morrison, Slavery and the American West: The Eclipse of Manifest Destiny and the Coming of the Civil War (Chapel Hill: University of North Carolina Press, 1997), 126-56; Michael F. Holt, The Political Crisis of the 1850s (New York: John Wiley & Sons, 1978), 101-81; David M. Potter and Don E. Fehrenbacher, The Impending Crisis, 1848-1861 (New York: Harper & Row, 1976), 177-224; U.S. House Journal. 1853. 33rd Cong., 1st sess., 923; Michael Burlingame, Abraham Lincoln: A Life (Baltimore: The Johns Hopkins University Press, 2008), 1:363-442.