The Kansas-Nebraska Act was passed by Congress on May 30, 1854. It repealed the Missouri Compromise and allowed for the expansion of slavery into new territories. The Missouri Compromise, which had been passed in 1820, prohibited slavery north of 36°30′ latitude in all new states north of Missouri’s southern border. This act allowed for the expansion of slavery into new territories, including Kansas and Nebraska.
In addition, this act led to an increase in tensions between the North and South because it created a situation where the number of slaves could increase dramatically if more people chose to move westward into Nebraska or Kansas. This led Northerners to believe that Southerners were trying to expand their influence over Congress by using their numbers (since there were more Southerners than Northerners), which would allow them to gain more political power in Washington DC.
The act led directly to a major conflict between pro-slavery forces and abolitionists over whether Kansas would become a slave state or a free state. This conflict became known as Bleeding Kansas, or “Bleeding” because it involved violence between pro-slavery and abolitionist settlers in Kansas, as pro-slavery forces from Missouri crossed over into Kansas and tried to take control of elections there.