The Kansas-Nebraska Act was passed by the U.S. Congress
in 1854 to allow people in the territories
to decide for themselves whether or not to allow slavery
within their borders. The Act
additionally served to repeal
the Missouri Compromise
The Kansas-Nebraska Act was passed much to the dismay of many anti-slavery northerners. The abolitionists, in particular, had felt that the Missouri Compromise was intended to be a long term settlement. Naturally, the act was highly favored amongst Southern voters.
After the Kansas-Nebraska Act was passed, pro-slavery and anti-slavery supporters rushed in to settle Kansas to try to manipulate the outcome of the first election held there. Pro-slavery settlers easily won the election but anti-slavery settlers cried foul, and the results were not accepted.
The anti-slavery settlers held another election, but this time the pro-slavery settlers refused to vote, resulting in the establishment of two opposing legislatures within the Kansas territory. As a precursor to the Civil War, violence soon erupted, with the anti-slavery forces being led by John Brown.
President Franklin Pierce sent in Federal troops to stop the violence and disperse the anti-slavery legislature. Another election was called. Once again pro-slavery supporters won and once again they were charged with election fraud. As a result, Congress did not recognize the constitution adopted by the pro-slavery settlers and Kansas was not allowed to become a state.
Eventually, however, anti-slavery settlers outnumbered pro-slavery settlers and a new constitution was drawn up. In 1861, just before the start of the Civil War, Kansas was admitted to the Union as a free state.