Y'all should watch a very cool series on the History Channel called "How the States Got Their Shapes". Its one of the few left that actually deals with history as opposed to pawn shops, antique dealers, and Larry the Cable Guy. But I digress. It talks about how Tx. was broken up, Nevada's secession from Utah, Idaho's separation from Mt. and the like. Its neat stuff.
As far as the legality of forming a new state, Article Four says the following:
New States may be admitted by the Congress into this Union; but no new States shall be formed or erected within the Jurisdiction of any other State; nor any State be formed by the Junction of two or more States, or parts of States, without the Consent of the Legislatures of the States concerned as well as of the Congress.
So it seems that the Co. Leg and Congress would have to approve. In the case of W.Va. that little nicety was overlooked as Va. had declared itself in rebellion, and Congress was happy to have a new ally. Nowadays? I doubt that permission would be forthcoming. But they could always follow Key West's example and declare themselves independent. Viva the Conch Republic.
