[Bubba Ho-Tep]

If states are not allowed to leave legally, why did the Confederate States have to be re-admitted?

The states weren't readmitted to the union because the U.S. position was that they'd never left. However, after walking out of Congress, their congressional delegations had to be readmitted to the House and Senate. Look it up.

[x]

The states weren't readmitted to the union because the U.S. position was that they'd never left. However, after walking out of Congress, their congressional delegations had to be readmitted to the House and Senate. Look it up.

That's true. That so many people use the word "readmitted" is an indication that the ex-Confederates must have had a very good PR firm.