The secession of the southern states from the Union was caused by decades of tension between the North and South on the issue of slavery in territories. It started with the Missouri Compromise in 1820 when Missouri wanted to enter as a slave state. The compromise ended with Missouri entering as a slave state, Main joining as a free state, to keep the balance, and slavery not being allowed north of the 36 30 N latitude. Three decades later another compromise had to be made to keep the balance in congress. The compromise of 1850.
