Here is some more information regarding various secessionist efforts in the United States:
As a child more than 1970s I remember seeing a little pamphlet/newspaper in a small mom and pop store.
The story on the cover was regarding efforts to found "Illiindmich"; which was the mass secession of Illinois, Indiana, and Michigan. They would break away and join together to form a new country.
Obviously, nothing ever came of it.
Short of a mass collapse of society and civil order, the US is not breaking up any time soon.