The United States is considered a mature country, they can handle their issues and ensure a civil war never breaks out. It is possible that they can go into a war with another country, but If asked the possibility of a civil war, I'd say it is highly unlikely, they are not called the United States for no reason.
If a second Civil War ever begins, it will probably be because the elites calling the shots found a way to make it profitable to themselves.
It's the people who can't think very well who join in a civil war. Meanwhile the thinkers among them reap profits wherever they see an opportunity.
For example, a shoe and boot maker doesn't have time to fight in a civil war, because he is making shoes and boots for both sides.
