What was the major issue between northern and southern states atfer 1820?

The major issue between northern and southern states after 1820 centered around the expansion of slavery into new territories and states. The Missouri Compromise of 1820 attempted to address this by delineating free and slave states, but it ultimately highlighted the growing sectional tensions. The North increasingly opposed the spread of slavery, while the South sought to protect and expand its slave-based economy, leading to deepening divisions that would culminate in the Civil War.