In 1820, the Missouri Compromise was passed as a way to stave off issues of sectionalism surrounding the number of slave and free states. Missouri was added as a slave state while Maine was admitted as a free one at the same time. Further, slavery would be declared illegal north of the 36o30' parallel west of Missouri. However on May 30, 1853, not only was the Missouri Compromise repealed but the Kansas-Nebraska Act was passed. This act allowed settlers of the Kansas and Nebraska territories to choose whether they wanted to be free or slave territories. Kansas would soon be called Bleeding Kansas due to the fighting that resulted from this act. This would be one of the main factors that led to the US Civil War.