Final answer:
The Kansas and Nebraska territories were formed to receive popular sovereignty, allowing settlers to determine the legality of slavery within these areas, a circumstance directly related to the Kansas-Nebraska Act of 1854.
Step-by-step explanation:
The territories formed to receive popular sovereignty were Kansas and Nebraska. This is in accordance with the Kansas-Nebraska Act of 1854, which allowed the settlers in these territories to decide for themselves whether to allow slavery within their borders. This principle was part of a series of measures attempting to address the contentious issue of slavery in the United States leading up to the Civil War.
The Kansas-Nebraska Act essentially repealed the Missouri Compromise, which had prohibited slavery north of the 36° 30' latitude line. The Act led to significant unrest, including violence in Kansas, an event known as "Bleeding Kansas", as pro-slavery and anti-slavery settlers rushed into the territory to affect the outcome of the first election held there after the passage of the Act.
Despite the intentions of Stephen Douglas and other lawmakers to ease tensions with the principle of popular sovereignty, it, in fact, increased sectional strife, setting the stage for the Civil War by undermining political compromises that had previously kept the union together.