The correct answer to this open question is the following.
I think what could have happened to the nation if the Missouri Compromise had not passed was that events, incidents, differences, and debates would have caused the premature beginning of the American Civil War in 1820.
Those years were a time of too much tension. The issue of slavery had already divided the nation.
That moment really illustrated the dichotomy of American society's attitudes about slavery in the early 19th century.
The context of the Missouri Compromise of 1820 was that there were many problems with slavery in the states. Some approved and depended on slavery, others -mostly the Northern states- disapproved and supported desegregation. In 1819, Missouri asked to enter the Union as a slave state, breaking the balance between supporters and non-supporters. By passing the Missouri compromise, the US Congress had an opportunity to soothe the complicated situation. It granted the Missouri request, and at the same time, Main was admitted as a free state.
