Answer
Countries and States are generally already present out of the box in IFS's standard Basic Data setup, so the remaining work is populating Counties, Cities, and Postal/Zip Codes underneath them. Since there's no built-in live feed for this reference data, source it from a trusted external data provider, keeping in mind this kind of geographic data does change over time so you'll need to decide how often to refresh it, and load it into IFS via a series of Migration Jobs working top-down through the hierarchy: first add Counties to their States, then add Cities to their Counties, then add Postal/Zip Codes to their Cities. Spreadsheet-based migration jobs are straightforward for this kind of relatively simple, already-modeled reference data.