ISO 3166-2: Codes for Country Subdivisions

Structure and examples

Each ISO 3166-2 code has two parts separated by a hyphen. The first part is the ISO 3166-1 alpha-2 country code; the second part is a short sequence (one to three characters) chosen by the maintenance agency to represent the subdivision. The second part may consist of letters, numerals, or a combination. For example, the United States uses codes such as US-CA for California; other countries use numbers or mixed codes—for instance some French departments appear as FR-75. For details on country identifiers see ISO 3166-1.

History and maintenance

The list was created to harmonize how subdivisions are referenced across international systems and databases. The ISO 3166 Maintenance Agency (ISO 3166/MA) oversees updates: codes can be added, changed or deleted when political or administrative arrangements evolve. The maintenance agency operates under the International Organization for Standardization; information about the organization is available at ISO.

Uses and significance

ISO 3166-2 codes are widely used in data exchange, statistics, logistics, mapping, software localization and geocoding to ensure clear, language‑neutral references to regions. They support interoperability between national registries, shipping systems, statistical databases and many web services that require a compact, stable identifier for subdivisions.

Notable points and distinctions

Not every country has defined subdivisions in the standard; where no subdivisions are present, no ISO 3166-2 entries exist. These codes are separate from other systems such as FIPS or national coding schemes and are updated when official administrative changes occur. Because codes may change, systems that rely on them should implement update procedures and refer to the official resources for current lists and revision notices.