The Kansas-Nebraska Act was a federal law that was intended to give people more choice. Instead, it further enflamed the growing struggle between North and South over slavery.

The Missouri Compromise in 1820 had sought to keep the peace, as far as “slave” and “free” states were concerned. Maine, in the far north of the United States, was admitted in 1820 as a “free” state, meaning that slavery was prohibited within its borders. The namesake of the Compromise, Missouri, was admitted in 1821 as a “slave” state, meaning that its residents were not prohibited from owning slaves. Further, the Missouri Compromise prohibited slavery north of latitude 36°30' but not south of that line. Missouri was north of that latitude line, but Missouri was allowed to be an exception.

After that, more states entered the Union. Arkansas (1836) and Michigan (1837) kept the North-South balance, as did the foursome of Florida and Texas (both 1845) and Iowa (1846) and Wisconsin (1848). The balance tipped with the admission of California in 1850.

California had been part of Mexico until after the Mexican-American War. A concession to the U.S. from Mexico as part of the terms of the Treaty of Guadalupe Hidalgo was the Mexican Cession, a large handover of land. This included California and what are now several other states, including what became known as the Kansas-Nebraska Territory.

As more and settlers entered these areas, the issue of whether these new settlers could own slaves became more and more prominent. Supporters of both sides voiced their opinions, in their homes, in public, in the new territories, and in Congress.

At this time, the idea of Popular Sovereignty began to gain support. Championed by Illinois Senator Stephen A. Douglas (left), the idea was that the people of a territory should be able to decide for themselves whether they could own slaves, not abide by laws from the federal government. The entirety of the Kansas-Nebraska Territory was north of the latitude line stipulated by the Missouri Compromise, and so Southerners feared that the law of the land would allow several new “free” states, tipping the balance even further in the favor of opponents of slavery.

Popular sovereignty was already in evidence in the New Mexico Territory and the Utah Territory. Those two territories were part of the Mexican Cession but had not been part of the Louisiana Purchase and so were not American territory when the Missouri Compromise became law and, thus, not subject to it.

A non-slavery-related purpose of the Kansas-Nebraska Act was to enable the creation of a transcontinental railroad. For many eastern businessmen, the sooner the Kansas-Nebraska Territory was settled, the sooner a railroad through the Territory could be built and the sooner goods could travel more easily and quickly from coast to coast. Of special interest was the promise of vast quantities of new farm products, from the abundant farmland that made up the Territory.

As far back as 1845, Douglas, then a member of the U.S. House, had tried to organize the Nebraska Territory with an eye toward building a railroad. Douglas, from Illinois, wanted the railroad to run through Chicago. Other cities in other states, namely Memphis, New Orleans, and St. Louis, had supporters as well. One prominent support of the Kansas-Nebraska Act was Missouri Senator David Atchison, who wanted a railroad to run through St. Louis, in his state, not through Chicago, in Douglas’s state. In the end, no decision was made.

It took a few introductions of a bill to provide for the settlement of the Kansas-Nebraska Territory, but one that had broad support finally emerged. One of the authors of the bill was Douglas, who had also been an author of the bill that created the New Mexico and Utah Territories. The language of the bill intentionally resembled that of the Compromise of 1850.

The bill that eventually created the Kansas-Nebraska Territory, however, clearly repealed the Missouri Compromise. In essence, Douglas had championed the idea of popular sovereignty and won for this new territory the right for the territory’s settlers to choose their own destiny in terms of slave ownership. That such a policy was in opposition to the Missouri Compromise because the new territory was north of the latitude line clearly set out in the Missouri Compromise was not in doubt. Something had to give, and it was the Missouri Compromise that was reduced to a former law. Some observers had argued that the Compromise of 1850 had already done that.

The President at the time, Franklin Pierce, made it known that he supported the Kansas-Nebraska bill and its idea of popular sovereignty. Pierce made it clear that he supported Douglas, his fellow Democrat, and that others in the Democratic Party should be on board as well.

Both houses of Congress eventually approved the bill, and Pierce signed it into law on May 30, 1854.

The votes in both the House and the Senate were close, so the bill did not have overwhelming support. This was the case in the population at large as well.

The struggle for popular sovereignty was particularly harsh in Kansas, which in the next few years turned into a battleground, politically and literally. Large numbers of Missourians crossed the border into the newly created Kansas Territory, aiming to influence that new territory’s vote on whether slavery would be allowed. Controls for voting were not very well maintained, and subsequent votes of supposedly Kansas Territory residents on the question of slavery contained as well a fair number of Missouri residents. These slavery advocates formed into groups in some cases, to prevent a united front; some of the more well-known of these kinds of groups were the Blue Lodges and the Sons of the South.

Advocates of the abolition of slavery, called abolitionists, pressed their case in Kansas as well. Somewhere along the way, the name “Jayhawkers” got attached to these anti-slavery advocates, particularly the ones who favored a solution to the slavery problem that involved armed conflict.

One abolitionist who was no stranger to armed conflict was John Brown (right), who came to prominence for his involvement in two violent episodes in Kansas. In May 1856, pro-slavery forces sacked the free-state capital at Lawrence; in response, Brown and his sons killed five pro-slavery farmers in the tiny settlement of Pottawatomie. In August of that same year, Brown was involved in a tense clash between abolitionists and pro-slavery forces at the small town of Osawatomie: Brown and a few dozen men held off a few hundred opponents before retreating; the victors stormed into the town and burned it.

As of a result of this and other violence, the territory came to be known as “Bleeding Kansas.”

Less violent abolitionists in Kansas were called "Free-staters." It was their persistence, along with the sheer numbers of anti-slavery settlers who descended on the territory, that eventually carried the day, and Kansas entered the Union as a free state in January 1861.

Several Southern states had already seceded by the point, and the Civil War began later that year. The President during the Civil War, Abraham Lincoln, had gained prominence for his opposition to the policy of popular sovereignty, especially in a series of debates with Douglas called the Lincoln-Douglas Debates.

Nebraska, meanwhile, traveled on a less violent, more meandering path, being admitted to the Union in 1867. By that time, the Civil War had ended and the Thirteenth Amendment had abolished slavery.