Was the US Civil War inevitable? How inevitable was it?

I believe it was inevitable simply due to the fact that the country was so polarized along geographical lines. Secession was a natural thought for anyone of rational mind, it was the actual pursuance of secession that was the spark that lit the fires of war. As simplistic as some would have you believe, slavery wasn't the only issue. There were the social and economic factors as well. What do you think? Why?