Answer: above the Missouri Compromise line.
Step-by-step explanation:
The Kansas and Nebraska territories were located above the Missouri compromise line which meant that they would be Free states when they gained statehood.
The South didn't want this as it would increase the number of free state representatives in Congress and so tried to block statehood. This led to a conflict in Kansas as Pro and Antislavery activists clashed. This was called "Bleeding Kansas".
The Antislavery activists eventually succeeded and Kansas joined the U.S. as a Free state.