The Kansas-Nebraska Act was enacted on May 30, 1854. This piece of legislation created the territories of Kansas and Nebraska and allowed the settlers in those territories to determine whether they would allow slavery within their borders, a concept known as popular sovereignty.
"Bleeding Kansas" refers to the violent conflicts that erupted in Kansas between pro-slavery and anti-slavery factions in the years following the act's passage, especially between 1854 and 1859. This period of conflict was marked by significant violence and is considered a precursor to the American Civil War. The term "Bleeding Kansas" was popularized in the 1850s as reports of the violence and turmoil in the region became widely circulated.