The event that most clearly marks the beginning of the sectional crisis that led to the outbreak of the Civil War was the Missouri Compromise of 1820.
The Missouri Compromise of 1820 was a treaty between slave and abolitionist states in the United States. The treaty was added to regulate slavery in the United States.
The Missouri Compromise meant that in all states north of 36 ° latitude, except Missouri and states east of Missouri, slavery would be banned. In states south of the latitude, it could be allowed if the authorities and the free population so desired.
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