Final answer:
The Kansas-Nebraska Act, introduced by Senator Stephen Douglas in 1854, sought to divide the Nebraska Territory and apply popular sovereignty to determine slavery, leading to heightened tensions that precipitated the Civil War.
Step-by-step explanation:
The bill in question, introduced by Senator Stephen Douglas in January 1854, was known as the Kansas-Nebraska Act. This significant piece of legislation proposed that the vast Nebraska Territory be divided into two separate territories: Kansas, adjacent to Missouri, and Nebraska, adjacent to Iowa. The act notably employed the principle of popular sovereignty, allowing the settlers in both territories to decide the issue of slavery for themselves. Douglas's intent behind the bill was multi-faceted, aiming to bolster his political position, facilitate the construction of a transcontinental railroad through Chicago, and keep his party, the Democrats, united despite internal conflicts and the contentious issue of slavery. The Kansas-Nebraska Act fundamentally altered the political landscape by repealing the Missouri Compromise's 36° 30' line, leading to increased tensions between pro- and anti-slavery factions and significantly advancing the country toward the Civil War. The resulting clashes in Kansas, known as 'Bleeding Kansas', highlighted the violent struggle over the sovereignty of the states in matters of slavery.