POPULAR SOVEREIGNTY In American history, the term "popular sovereignty" (or "squatter sovereignty") refers to the nineteenth century doctrine which stated that the inhabitants of a territory had the right to decide for themselves whether they wished their territory to be admitted into the Union as a "free state" or as a "slave state." Formulated by Senator Lewis Cass of Michigan and strongly supported by Senator Stephen A. Douglas of Illinois, the concept of popular sovereignty was initially employed in the Compromise of 1850, which provided that the inhabitants of the New Mexico and Utah territories should decide for themselves whether they wished to be "free" or "slave" upon petitioning for statehood.
In 1854, the concept was used again, but with fatal repercussions. The Kansas-Nebraska Act of 1854 provided that Kansas and Nebraska, upon fulfilling the prescribed requirements for statehood, could enter the Union on the basis of popular sovereignty. The tragic aspect of this measure (and, hence, the tragic nature of the concept itself) was that it nullified the Missouri Compromise of 1820 (Kansas and Nebraska were north of the line thirty-six degrees and thirty minutes, a territory from which the Missouri Compromise had specifically excluded slavery), and it opened Kansas (which presumably was much more suitable than Nebraska for a plantation-type economy) to an organized migration of proslave and antislave groups determined to gain control over the territory for their own avowed interests. The result of this, of course, was a bloody civil war in Kansas between these two groups — a conflict which earned the territory the dubious distinction of being called "Bleeding Kansas." In other words, although the concept of popular sovereignty might have looked good on paper, in practice — at least in the case of Kansas — it was a fiasco. See also: KANSAS-NEBRASKA ACT and MISSOURI COMPROMISE.