Easily, the South.
If not for our natural gas and oil and Gulf resources, the northeast would freeze in the dark. We have the cotton, to boot. The South could survive without the rest of the nation, but it would be hard for the other parts to survive without the South.
Also? The Second Amendment
means something down here. We own guns, know how to use them, and will defend the Constitution WITH them...get the drift?
And will also defend any enroachment on our rights...just as did our Confederate great-grandfathers....
Hopefully it wont happen....but if it does? We won't lose, if a next time ever comes...