Tom,
First and foremost, do not alter the card(s). Making even a minor change
will invalidate a card for many awards programs. Best bet, when you find
out what county a station is in, is to use a post-it note or similar method
to indicate what the card is for -- something that does not physicall
Listings on QRZ.com cannot be relied on, since it lists mailing address which may not be in the same county as the station, or may be old info.
Get a good Rand Macnally{SP?} Road Atlas which shows county boundaries. Look up the town in the index in the back, then find it on the state map to determi