The Civil War

1. Economic Differences- The southern states economic system was based upon slave labor and without it, the system would have failed and the south would also probably lose some of their political influence as well.
2. States Rights-The southern states and northern states had separate and different economic systems that relied upon different methods in order to make it work successfully. I believe the problem with states rights gained attention when newer states were being created and whether or not they were going to be operated with the southern influence or the north's (including political power).
3. Slavery-Slavery was viewed as an economic issue by the south and as a moral issue in the north. I believe slavery became a problem when the south tried to spread slavery to other states in order to gain more political power and the north used slavery as a tool against the south in order to justify the war.
4. Election of Lincoln-Lincoln was against slavery and was elected the president of the country. The southern states decided to secede from the union and form their own confederacy. If the south would have won the election, there would have been problems with the northern states. When the south did secede from the union, it was viewed as a hostile act and gave the north more of a reason to justify the war.
5. Rise of Abolition Movement-The abolitionists were against slavery, so they embraced Lincoln and supported the war.

References:
What caused the American Civil War?
http://www.greatamericanhistory.net/causes.htm
Causes of secession
http://en.wikipedia.org/wiki/American_Civil_War