The Confederate States of America was an illegal organization and thus everything done by the CSA was illegal, even things which would have been legal if done by legal governments. Therefore, a large percentage of the USA was taken over by criminals and ruled by those criminals for up to four years in some places.
In fiction, the movie serial Buck Rogers (1939) shows the USA and the entire planet Earth, except for the Hidden City, taken over and ruled by a crime c syndicate led by "Killer" Kane.