Yes, the fact that postal addresses don't coincide with city/county limits makes it more confusing. It all boils down to whatever locality the residence lies in.

One example:

Radford is an independent city (like Norton) whose school system attendance zone is the city limits. But the Radford post office delivers not only to the entire city of Radford, but to portions of Montgomery, Floyd and Pulaski County. Therefore if you see a Radford address it's possible for it to be in any one of FOUR localities.