USA County Verifier
When you exit a location field on the Individual Information, Marriage, or Event screens, Legacy checks the validity of county names for locations in the United States (if the Verify USA Counties in Place Names option is turned on the Data Entry tab in the Customize section). An warning is shown if:
No county by that name by that spelling was ever found in that state.
The county was not in existence in this state at the date specified.
The county had been dissolved in this state before the date specified.
When an error is reported, you can choose to view a list of all the counties in that state to see when they were founded and their term of existence. See USA County Verification List.