American politics and culture during the 19th century was defined almost exclusively by slavery and its expansion. Before the dawn of 1800, slavery was accepted by many in its current boundaries. Yet with the addition of new territory and states, slave owner and pro slavery congressmen sough to expand slavery out of the South. Abolitionists opposed this expansion and ultimately sought the destruction of slavery. While the Civil War decided the issue of slavery for America, it was the actions of abolitionists who brought America to the brink of war and then pushed it over the edge.
At the dawn of the 19th century, slavery was largely a southern thing, although slavery still existed in some parts of the north. Its existence was tolerated because many felt that slavery was something that would just die out. However in 1803 congress and president Jackson approved the purchase of territory to which the French laid claim. This would become known as the Louisiana Purchase and it would breathe a breath of life into the lungs of slavery.
The Louisiana Purchase added a huge swath of territory to the holdings of the United States. Americans from the South and the North alike flocked to this new territory in the hopes of new beginnings. It was not long before territories were being formed out the purchase land and began applying for statehood. When Missouri applied to become a state, it ignited a debate in congress about whether or not Missouri would be a slave state or a free state. The debate in Congress about Missouri's slave stance was a moral and a political debate. On one front, you have those who are either morally against or for slavery. On the other front, you have those who realized that the balance of power in Congress could be shifted if a pro-slavery state was added to the Union and vice-verse. This gave the appearance to many that Congress was just playing politics than trying to solve an issue.