The Kansas-Nebraska Act allowed white American citizens living in Kansas and Nebraska territories to decide themselves if they wanted slavery to be allowed within their borders. The act enraged Northerners and pleased Southerners. Many pro-slavery and anti-slavery citizens rushed to the territories in an attempt to affect the election.
Cause: Kansas and Nebraska want to enter the Union.
Effect: Repeals the Missuori Compromise, allowing both to enter as free or slave, as voted by citizens.