A civil war in the current United States would not look at all like what people imagine, or the Civil War from 1861-1865.

It’d manifest more like the Rwandan Genocide combined with the political violence of the late 1960s and 1970s. Mostly, it’d be right-wingers killing Democrats, liberals and leftists with some retaliatory attacks going the other way “justifying” the attempted purge.

It might turn into a wider war, but that’d require geographical sorting that I find unlikely. Even most red cities are ~35%+ blue for instance.

So it’d be nasty. And long-running. And you would not like it. The economy would crash and food shipments would be disrupted. Some areas would starve in the worst cases.

But it’s certainly possible. I give the above scenario a 15% chance in the next decade, which is way way too much.