What was one of the primary effects of the Kansas-Nebraska Act?

The Kansas-Nebraska Act, passed in 1854, had profound implications for the issue of slavery in the United States. The act allowed for the territories of Kansas and Nebraska to decide for themselves whether they would allow slavery, under the principle of popular sovereignty. This led to significant tensions as both pro-slavery and anti-slavery settlers moved into these territories, each aiming to influence the outcome of the vote regarding slavery.

The conflict that ensued, known as "Bleeding Kansas," was marked by violent confrontations between the two factions. This violence stemmed from increasingly polarized views on slavery and revealed the intense national divisions on the topic. The term "Bleeding Kansas" itself reflects the chaos and bloodshed that accompanied the struggle for control over the new territories, showcasing the deepening sectional conflict that would eventually lead to the Civil War.

While the act did indeed open up lands for westward expansion and highlighted the contentious issue of slavery, it did not resolve the disputes surrounding slavery; instead, it exacerbated them, leading to violence and conflict. The other options do not capture the immediate consequences of the act as accurately as the rise to violence did.