[Movemout]

"If it takes approval of the Fed Congress to change a state boundary how in the world would it be constitutional for a state to drop out of the union? "

An interesting question- if you are from Texas, as your nick implies, you might note the unusual conditions that Texas imposed on the USA prior to joining the union. One was the right to secede from the USA. r9etb has written a nice piece here but it ignores the context in which the union was formed. I do not think that any state was willing to concede its existence to the power of a federal authority.

[Texaggie79]

Some states would have more reason, however what right would states such as in the Louisiana purchase have to leave the very nation that purchased it?

[Non-Sequitur]

Can you provide a link to the document that shows the United States granted Texas the right to secede?