By 1858 there was only one national political party left, the Democrats. The one thing that kept them together was the concept of Popular Sovereignty that meant that individual states and territories could decide for themselves to be free states or slave states. Under this idea the local people made the choice and not Congress. This way Northern and Southern Democrats would continue in the same party. However, the Dred Scot decision eliminated the idea of Popular Sovereignty by declaring all states and territories were open to slavery because the 5th Amendment guaranteed private property which slaves were. So, no states were allowed to be free. With Northern Democrats still supporting Popular Sovereignty and now Southern Democrats claiming it was illegal the last remaining national party fell apart. The last institution that held the nation together was gone.
Historically Speaking 