FIPS codes explained

How the codes are built

The codes began as Federal Information Processing Standards. Census now publishes them as ANSI codes and calls the combined value a GEOID, but most people still say FIPS. The 5 digit county code is the key that joins Census, BLS, CDC, and many other county tables.

There are 51 state-level codes for the 50 states and DC, and 3,144 county-level codes in the 2024 data. State codes run from 01 to 56 with gaps, so a state's code is not its position in the alphabet.

How county numbers are ordered

County codes are mostly odd numbers that roughly follow the alphabetical order of the county names. The data shows how far that pattern holds today. Of 3,093 county-level codes outside independent cities, Connecticut and DC, 3,060 (98.9%) are odd.

In 24 of the 49 states with more than one county and no planning regions, sorting by code gives exactly the alphabetical order of the names. In the rest, at least one county is out of order, so never guess a code from a name; look it up.

Codes of the ten most populous counties

Independent cities, Alaska, and Connecticut

Independent cities have county-level codes of 500 and above, for example Richmond city, Virginia (51760), distinct from Richmond County (51159). In Alaska, the Census Bureau split the Valdez-Cordova Census Area (02261) into Chugach (02063) and Copper River (02066) effective January 2, 2019.

Connecticut's former counties used 09001 to 09015. In 2022 the Census Bureau adopted the state's nine councils of governments as county-equivalents, and current data uses planning region codes 09110 to 09190. Files from before and after the change will not join on county codes.

Joining spreadsheets on FIPS

Store codes as text so leading zeros survive: Alabama's Autauga County is 01001. In Excel use =TEXT(A2,"00000") to repair a column that lost its zeros. Match on the 5 digit code, not the name, since names repeat within a state and vary in spelling. The common county names guide shows how often names repeat across states.

Checking a column of codes

A few rules catch most bad codes. Every county code is five digits. The first two digits must be a valid state code, and in this data every county code starts with its own state's code. The last three are between 001 and 840, and codes of 500 or more mark independent cities in the four states that have them. Texas also uses codes above 500 for ordinary counties, because it has so many.

If a column has four digit values, it lost a leading zero: the seven states coded 01 to 09, Alabama to Connecticut, are affected, and 318 county codes begin with a zero. If a code does not appear in the current list at all, it may be an older code that changed, such as the Connecticut and Alaska cases below.

Finding a code

The lookup tool below searches all 3,144 codes by county name, state or code. If you know where you are but not the county, the what county am I in tool finds the county from your location and shows its code. Every county page on this site also lists its code in the header.