How did the Kansas-Nebraska Act of 1858 impact sectional tension?

The Kansas-Nebraska Act of 1854, not 1858, significantly impacted sectional tension by reopening the contentious debate over slavery in the northern territories. Prior to the Act, the Missouri Compromise of 1820 had established a clear boundary (the 36°30' parallel) that determined where slavery could and could not expand in the west. The Kansas-Nebraska Act effectively nullified this compromise by allowing the settlers in those territories to decide for themselves whether to allow slavery through the principle of popular sovereignty.

This legislation led to a violent struggle known as "Bleeding Kansas," as pro-slavery and anti-slavery factions rushed to the territories to influence the outcome of elections and establish their dominance. The resulting conflict exemplified the deepening divisions between the Northern and Southern states regarding the issue of slavery, leading to increased animosity and a clearer alignment of political factions according to their stance on slavery. Therefore, the Act did not resolve tensions; rather, it exacerbated them, making it a pivotal moment in the lead-up to the Civil War.