MetroWhig takes the discussion a bit further:

It would not surprise me at all to see a civil war within my lifetime, and I think it's the one thing that would make me leave the country because I don't think it will be "won" without destroying all the things that make this country great.

I don't see the next civil war ending in anything other than a totalitarian 1984-ish state; There's too much high technology out there for it to end any other way, and too little education in the broader population to prevent it from going this way.

I'd have to say I would be very surprised by a civil war in my lifetime.  For one thing, the national government is way ahead of that curve.  That's what gun control is all about.  So the most likely scenario would involve a split within the military, a scenario most unlikely given its structure and civilian control.  While citizens do have guns and ammo, they're going to be no match for the government.

There is the guerilla option, which is more likely, but it would cause such destabilization that I doubt many at all would be willing to endure the disruption of their lives long enough to tolerate the randomness of such tactics.  For those who will be quick to point out the success of guerilla style resistance movements, let me point out that such movements were culturaly enabled.  We are not the Vietnamese, nor are we the Iraqis.

Finally, what issue would set it off?  The big debates now are over immigration, abortion and the war.  I can see the immigration debate sparking a conflict along racial lines, but that would be more like a foreign war than a proper civil war.  Abortion has commonalities with slavery, but the all important economic factor isn't there...at least yet.  I suppose I can imagine a "life states" vs. "death states" split developing different economic interests.  I don't know what those differences would be, but they would have to be great enough for people one hundred years later to debate whether the real cause of the Second Civil War was abortion or economics.

I think we're too lazy and effeminate to fight a civil war.  Or perhaps that just means the good guys will win an easy one.

My Mind is Clean