Usually, the "associated state" is the state in box 15 on that line on the W-2. The locality name in box 20 should be some help.
It's probably not needed for anything an can be ignored.
That said, a quick internet search (plus this excellent summary of local taxes https://ttlc.intuit.com/questions/4094807-having-studied-some-of-the-complaints-that-different-users...) indicates there are no local income taxes in either NC or SC.
Exactly, what is in boxes 18-20 on your W-2?
