Secession from a State
There will be a ballot proposition in California this year asking voters to approve dividing the state into six states. This plan is a one-way ticket to Nowheresville, as Congress would never agree to a division of the state, but it does raise some interesting structural issues.
Article Four of the Constitution provides that “no new State 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.” Why did the Framers feel the need to spell this process out? The answer, I think, is that in 1787 some of the original 13 states had uncertain territorial claims outside of their boundaries. Maine, for example, was claimed by Massachusetts. Kentucky was originally claimed by Virginia. And so on. Thus, there was a need for a procedure that would address how to handle statehood petitions coming from these areas, and some of the states probably wanted some assurance that they could not be divested of their claims without their consent. It’s a robust guarantee of state integrity.
Another point that often gets overlooked, though, is that Article Four expressly permits secession from a State. If the state and federal governments consent, then a disgruntled part of a state can leave. (The only example is West Virginia during the Civil War, which was problematic because the illegal government in Richmond did not agree to this secession.) The presence of this state secession provision could imply that secession by an entire state was not permissible, though that sort of textual argument is always tricky.