It could happen, but it would require the consent of Congress and the states.
Unilateral secession is expressly unconstitutional.
Expressly where exactly in the Constitution?
No it isn't. The constitution says absolutely nothing on the subject because the constitution was written only 11 years after the declaration, which says everything that needs to be said on the subject.
Come on you know there is nothing in the USC making secession unconstitutional. You know better.
Oh, the death of literacy! Words mean things and "expressly unconstitutional" means that this supposed unconstitutionality is expressed somewhere in the constitution. Please tell us where in the constitution your claim is expressed. "Expressly" does not mean 'very' or 'I feel strongly'.