How did the Kansas-Nebraska Act affect the North and the South?

The Kansas-Nebraska Act proposed that these territories, after being organized, should be allowed to decide for themselves whether or not to allow slavery. This principle, called popular sovereignty, was espoused by the bill's author, Stephen Douglas, an Illinois Democrat who hoped that opening the region to settlement might lead to the construction of a transcontinental railroad with its terminus in Chicago. The bill outraged many in the North because it repealed the 1820 Missouri Compromise, which had banned slavery in territories within the old Louisiana Purchase above a line drawn at 36'30 latitude. Many of those angered by the Act formed the Republican Party, which was created for the express purpose of arresting the spread of slavery. Southerners generally supported the bill, but eventually rejected its core idea of popular sovereignty due to the possibility that a territory could ban slavery from its borders. As it turned out, popular sovereignty in practice was catastrophic. Pro-slavery Missourians poured into Kansas to establish a pro-slavery government there against the wishes of a majority of Kansans. Bloodshed ensued in what became known as "Bleeding Kansas."