Most Expensive counties in USA - America's Richest Counties CountystateTime ZoneNassau (Nassau county NY Zip Codes)NYEasternDouglas (Douglas county CO Zip Codes)COCentralFairfax (Fairfax county VA Zip Codes)VAEasternSanta Clara (Santa-Clara county CA Zip Codes)CAPacificMontgomery (Montgomery county MD Zip Codes)MDEasternSomerset (Somerset county NJ Zip Codes)NJEasternPutnam (Putnam county NY Zip Codes)NYEasternMontgomery (Montgomery county MD Zip Codes)MDCentralMorris (Morris county NJ Zip Codes)NJEasternCalvert (Calvert county MD Zip Codes)MDEasternWilliamson (Williamson county TN Zip Codes)TNCentralMorris (Morris county NJ Zip Codes)NJCentralCharles (Charles county MD Zip Codes)MDEasternPutnam (Putnam county NY Zip Codes)NYCentralArlington (Arlington county VA Zip Codes)VAEasternHunterdon (Hunterdon county NJ Zip Codes)NJEasternDouglas (Douglas county CO Zip Codes)COPacificAlexandria City (Alexandria-City county VA Zip Codes)VAEasternDouglas (Douglas county CO Zip Codes)COMountainPrince William (Prince-William county VA Zip Codes)VAEasternLoudoun (Loudoun county VA Zip Codes)VAEasternHoward (Howard county MD Zip Codes)MDCentralHoward (Howard county MD Zip Codes)MDEasternForsyth (Forsyth county GA Zip Codes)GAEasternMarin (Marin county CA Zip Codes)CAPacificDouglas (Douglas county CO Zip Codes)COEasternStafford (Stafford county VA Zip Codes)VAEasternStafford (Stafford county VA Zip Codes)VACentral