FIPS Code
Federal Information Processing Standard code — a numeric identifier assigned by the U.S. government to states, counties, and other geographic entities for use in data processing.
FIPS codes are standardized numeric identifiers originally established by the National Institute of Standards and Technology (NIST) to ensure consistent identification of geographic entities across federal databases. FIPS state codes are 2 digits (06 for California, 36 for New York), and FIPS county codes add 3 digits (06037 for Los Angeles County).
Although NIST withdrew the FIPS geographic code standard in 2008, the Census Bureau continues to maintain and use identical codes under the name GEOID (Geographic Identifier). The codes remain essential for linking Census data, ZIP code databases, and administrative records.
FIPS codes are embedded in many postal code databases to enable ZIP-to-county mapping. Since a single ZIP code can span multiple counties, databases typically list the primary FIPS county code for each ZIP alongside any secondary county overlaps.