Why did new problems spread of Slavery come up after Missouri compromise?

The Missouri Compromise of 1820 aimed to balance the power between free and slave states by admitting Missouri as a slave state and Maine as a free state. However, it did not resolve underlying tensions over slavery, particularly as westward expansion continued. The compromise established a geographic line that divided free and slave territories, but as new states sought admission to the Union, debates over their status reignited, leading to increased sectional conflict. This ultimately set the stage for further crises, such as the Kansas-Nebraska Act and the rise of abolitionist movements.