Final answer:
Stephen A. Douglas's Kansas-Nebraska Act proposed the organization of Kansas and Nebraska territories, allowing for the possibility of slavery within them according to popular sovereignty, contrary to the Missouri Compromise's restrictions.
Step-by-step explanation:
Stephen A. Douglas proposed creating two territories with the introduction of the Kansas-Nebraska Act. This act ultimately might allow slavery in Kansas and Nebraska territories, which went against the restrictions set by the previous Missouri Compromise. Douglas's intention was to facilitate the building of a transcontinental railroad through Chicago, which would require organizing new territories for its passage. Additionally, the Kansas-Nebraska Act applied the principle of popular sovereignty, leaving the decision to allow or disallow slavery up to the settlers in those territories—a point which increased political tension and division surrounding the issue of slavery.