If you read the first of our Tips on FIPS series, you now know what these codes are and where they come from. So, let us continue with a bit about how they are organized.
The state/county ANSI/FIPS code is a combined 5-digit number; the left 2 digits refer to the state and the right 3 digits to the county. These 5-digit IDs provide a unique identifier for each geographic entity. Within the nation, each state ID is unique, and nested within the state, each county ID is unique.
It is important to remember that these numbers always include leading zeros. So, the first state is listed as ‘01’ and not just ‘1’; and, the first county as ‘001’. The next step is to simply string them together, as ‘01001’. So, for example, Washington County (143) in Arkansas (05) is listed as ‘05143’, while Washington County (167) in Ohio (39) is listed as ‘39167’.