- In 1819, Missouri wanted to be admitted as a slave state, but the House passed the Tallmadge amendment: no more slaves could be brought to Missouri. Southerners saw the Tallmadge amendment as a threat to sectional balance and overthrew it in Senate.
- The North dominated the House, but the North and South were equal in the Senate (11 free states and 11 slave states).
- In 1820, Congress agreed to admit Missouri as a slave state, but made free Maine (once part of Massachusetts) a separate state. Also prohibited all slavery in Louisiana Purchase territory north of 36'30 (the southern boundary of Missouri),
- Significance: Put forth the issue of slavery, and the sectional balance. Also set a precedent for compromise to keep things equal in the Senate. This compromise would be broken in 34 years, when more land would be acquired for the United States. This compromise temporarily pushed the slavery issue away.