This is the CodeSystem that contains all the codes in Federal Information Processing Standards Publication: Counties and Equivalent Entities of the United States, Its Possessions, and Associated Areas (FIPS 6-4) (http://terminology.hl7.org/CodeSystem/FIPS64) and Federal Information Processing Standards Publication: Counties and Equivalent Entities of the United States, Its Possessions, and Associated Areas (FIPS 6-4) (http://terminology.hl7.org/CodeSystem/FIPS64). E.g. what you have to deal with if you get resources containing codes in either of them