The Civil War happened due to the many differences between the North and the South. For example economic, social, cultural and political differences. These all helped lead America to a Civil War. But to an extent, the most important cause was the fact there were many disagreements with states' rights versus federal rights.
It was clear that there was always going to be a conflict between the federal government and the state governments because the federal government has the power to discuss bills and proposals for new laws. Whereas the state governments only has power to deal with policing, education and health care. And issues like slavery created tension between the two because the federal government wanted to abolish slavery but the southern states disagreed with this as this was their way of life and it should be their decision to abolish it or not. "Southerners believed that state laws carried more weight than Federal laws, and they should abide by the state regulations first." (http://americancivilwar.com/kids_zone/causes.html) It was mostly the southern states that didn't want to abolish slavery and most of the northern states went along with the federal government, so this caused a clash between the North and South and divided the whole nation. In addition, the South claimed that because of the Tenth Amendment, which declares that any power that is not granted to the federal government in the constitution is given to the individual states in the Union. So this means that any state is free to make laws outside the constitution for their own area of authority. Therefore the federal government has no right to abolish slavery in every state against their will. But then again the federal government has to maintain the authority so they can overrule the state laws, so they can make sure that everyone is treated equally. As the historians Sean Wilentz and John Ashworth describe, the North's commitment to