Why did southern whites feel threatened by the missouri compromise?

The Missouri Compromise was passed into a law in 1820 and was important an important law as it led  to the American Civil War. It was formulated by Henry Clay, a senator from Kentucky and was passed into law by James Monroe in 1920. The law caused extreme tension between pro slavery and anti-slaver states as there were equal number of pro and anti slavery states. But when Missouri requested to become slave states it caused tension as it could have tip the balance towards slave states. Although Missouri compromise added Missouri as a slave state, simultaneously it added Maine as a free state. The compromise banned slavery in the Great Northern Plains of Louisiana Territory, this line came to be known s Missouri compromise line. This compromise ended with Kansas-Nebraska Act in 1854.  The southern states felt threatened with the compromise because they considered that the compromise was meant to end the slavery in southern states.

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