It may be now but it wasn't then. A government derives its authority from the consent of the people it governs. If those people want to leave that government (and they comprise a large enough and unanimous area to do it) then they should be allowed to.
The civil war destroyed states rights.
And our government obtained that authority, as authorized by its Congress, and ratified by the people of the several states. Once the Constitution was ratified, it had supreme authority.
If those people want to leave that government (and they comprise a large enough and unanimous area to do it) then they should be allowed to.
It's always fun to make up rules as you go, but that isn't what was agreed to. Some folks say each individual ought to be able to "secede". What makes a group "large enough." What authority does that give them? Sorry, but the truth is our government obtained its authority, and the people and states were bound to it.