What do you believe to be the primary causes leading to the Civil War?

What do you believe to be the primary causes leading to the Civil War? Why?Some numerous issues and events led to the Civil War other than just slavery. You should notice that slavery wasn’t a primary cause of the war but became a significant issue during the war. Remember, we are not just looking at the days or weeks before April 1860 but we need to look back to 1789 when America became a country!