Emotion had a great deal to do with the conflict. On that topic, we have largely ignored emotional issues for the Northern public prior to the election of 1860.

Our discussions have largely been framed as the people of the Southern states against the Federal government. That's about as wrong as wrong can be. In the late 1850s Northern citizens were concerned because they viewed the presidency, the Supreme Court and Congress as being under control of slaveholders. What emotions would people feel who listened to the Lincoln-Douglas debates in the summer of 1858?

If we really want to understand (and I'm not sure anyone here really cares) what brought about the Civil War, we might do well to try to understand their side of the story. What generated strong emotions north of the Mason-Dixion line?

Related question: let's say slavery had been abolished in the United States twenty years after the Constitution was ratified. In 1860 there's no such thing as a slave state. What is the source of conflict between North and South? A good answer will be supported with specifics, not assumptions and rhetoric.