The following entities are considered to be equivalent to counties for legal and statistical purposes: The parishes of Louisiana; the boroughs and census areas of Alaska; the District of Columbia; the independent cities of Maryland, Missouri, Nevada, and Virginia; the portion of Yellowstone National Park in Montana; and various entities in the possessions and associated areas.

The values  to be used for this data element are described in FIPS 6-4, "Counties and Equivalent Entities of the United States, Its Possessions, and Associated Areas," dated August 31, 1990.

Important Notice:  Effective September 2, 2008, the National Institute of Standards and Technology (NIST) announced in the Federal Register, Volume 73, No. 140 (73FR 51276), that the Secretary of Commerce approved the withdrawal of 10 FIPS Publications, including FIPS 6-4. These FIPS were withdrawn because they are obsolete or have not been updated to adopt current voluntary industry standards, federal specifications, federal data standards, or current good practices for information security. 

Transition from FIPS to ANSI: The U.S. Census Bureau is the maintenance agency for the 2-digit and 3-digit codes for states, counties, and equivalent entities. The U.S. Geological Survey (USGS) is the maintenance agency for codes of named populated places, primary divisions of counties, and other locational entities covered under the former FIPS 55-3, "Codes for Named Populated Places, Primary County Divisions, and Other Locational Entities of the United States, Puerto Rico, and the Outlying Areas," dated December 28, 1994.  

The FIPS 55 guideline is being redesigned by the USGS to use the Identifier (ID) codes from the Geographic Names Information System (GNIS), which never change. This new proposed standard will be submitted for approval and accreditation by the American National Standards Institute (ANSI). Refer to the FIPS 55 PUBLICATION CHANGE NOTICE below, effective January 1, 2006, for USGS contact information and details on the proposed standard.

While the USGS has proposed adoption of the GNIS Identifier as the standard code for named places and county subdivisions, the GNIS ID for states, counties, and equivalent entities is a supplemental code that does not replace 2-digit state and 3-digit county codes maintained by the U.S. Census Bureau.

Visit the USGS GNIS web site to search or download electronic copies of names and codes for populated places, primary county divisions (such as townships and census county divisions), American Indian and Alaska Native areas, and Government units (states and counties). The GNIS is the Nation's official geographic names repository and has been designated by the U.S. Board of Geographic Names as the only source of geographic names and locative attributes for use by the Federal Government and its contractors.

The initial data standard and source data is available here:  County Name

Part 270, FW 6, Data Management and Standards, dated September 30, 2002.

FIPS 6-4, "Counties and Equivalent Entities of the United States, Its Possessions, and Associated Areas" dated August 31, 1990.

FIPS 55 PUBLICATION CHANGE NOTICE, effective January 1, 2006. Additional information on the content of this FIPS may be obtained from the USGS at 703-648-4544.

To ensure compliance with the Service Enterprise Architecture (SEA), Service staff are strongly encouraged to utilize this data element in existing systems, data sets, databases, and information applications. Where existing systems and data-related items are not in compliance, they should be modified to achieve compatibility and implement this data standard.

Counties in different states can have the same name. Therefore, in data systems concerned with the identification of counties in more than one State, the county names must be used in conjunction with the full State name and/or its corresponding two-letter alpha code.

The Service data standard for State Name and Alpha Code can be viewed at this site. It references the full State names and unique two-letter FIPS alphabetic codes for representing the 50 States, the District of Columbia and the outlying areas of the United States, and associated areas.

County names, State names, and the two-letter State alphabetic codes will be handled as separate data fields in any new or modified automated system, and will not be combined in a single data field.