the missouri compromise of 1820 was an agreement that slavery to be banned from the louisiana territory north of the parallel 36 degrees 30' north (also known as the missouri compromise line), except within the boundaries of the proposed state of missouri. it admitted missouri as a slave state to please the south and it also admitted maine as a free state to please the north. when the kansas-nebraska act was passed in 1854, it reversed the missouri compromise and caused a wave of resentment in the north. northerners believed it would cause missourians to cross the border into the kansas territory and take all the good land leaving nothing for northern settlers. northerners were pessimistic about the slavery issue. the president, his cabinet, both houses of congress and the supreme court of the united states were all pro-slavery. it was considered almost certain that slavery would dominate the united states.