Yes I realize that about the article. I just brought it up to suggest that maybe Ken Burns did not think that States Rights was the main issue. I read Lincoln's first inaugural address the other day. http://www.yale.edu/lawweb/avalon/presiden/inaug/lincoln1.htm
He obviously does not think the states have the right to leave the union. I honestly don't think you can separate out these issues, nor do I think that if slavery had not been an issue the civil war would have occurred.