Geographic Classification
TL;DR: WoT hosts 11 geographic classification systems anchoring the spatial axis: country codes (ISO 3166-1, UN M.49), subdivision codes (ISO 3166-2, EU NUTS 2021, US FIPS), feature classification (GeoNames Features), airport codes (ICAO Airport), climate zones (Köppen), and country development / income groupings (WB Income Groups, ADB Sector). Distinct from the country-link layer that maps a country to its applicable taxonomies - this page is the geography-as-classification view.
Country and territory codes
| System | Codes | Authority | Scope |
|---|---|---|---|
iso_3166_1 |
271 | ISO | Country / dependency / autonomous-region two-letter, three-letter, numeric codes |
un_m49 |
279 | UN Statistics Division | UN M.49 standard country / area / region codes (with regional groupings: SDG regions, geographic regions) |
ISO 3166-1 is the operational country code (US, GB, DE, etc.); UN M.49 layers in regional and sub-regional groupings (Northern America, Western Europe, Sub-Saharan Africa). Use both: ISO 3166-1 for the country, M.49 for any aggregation.
Subdivision codes
| System | Codes | Authority | Scope |
|---|---|---|---|
iso_3166_2 |
5,246 | ISO | First-order country subdivisions globally (US states, German Bundesländer, French régions, etc.) |
eu_nuts_2021 |
124 | Eurostat | Nomenclature of Territorial Units for Statistics (NUTS 1/2/3) |
us_fips |
86 | NIST (US) | Federal Information Processing Standards geographic codes (states + outlying areas) |
nuts_candidate |
11 | Eurostat | NUTS candidate codes for prospective EU members and candidates |
ISO 3166-2 is the universal subdivision code; NUTS is the EU-specific statistical hierarchy (NUTS 1 -> 2 -> 3); FIPS is the US legacy that many federal datasets still cite alongside ISO 3166-2.
Feature and place classification
| System | Codes | Authority | Scope |
|---|---|---|---|
geonames_features |
693 | GeoNames | Feature codes for places (administrative, hydrographic, populated, terrain, undersea, vegetation, spots/buildings/farms, roads/railroads) |
icao_airport |
21 | ICAO | ICAO airport-code regional groupings (KXXX = US contiguous, EXXX = Europe, etc.) |
GeoNames is the "what kind of place is this" classifier (a city, a river, a mountain, an administrative division). Use it alongside ISO 3166-2 to anchor a place: "Boston is P.PPLA (seat of first-order admin division) within US-MA."
Climate as geography
| System | Codes | Authority | Scope |
|---|---|---|---|
koppen_climate |
17 | Köppen-Geiger | Climate-zone classification (A tropical, B arid, C temperate, D continental, E polar, with subdivisions) |
Climate zones are not a coordinate but they classify where an observation can apply (a tropical zone Af city has different agricultural / disease / energy profiles than a desert BWh city).
Country groupings (development and macroeconomic)
| System | Codes | Authority | Scope |
|---|---|---|---|
wb_income |
27 | World Bank | Country income classification (low / lower-middle / upper-middle / high; updated annually) |
adb_sector |
46 | ADB | Asian Development Bank sector taxonomy with country-region context |
These are referenced from Financial Systems as well - relevant when development-finance or DFI activity is being classified.
Decision tree
| What you are doing | Use |
|---|---|
| Tagging a country | iso_3166_1 (always; the operational anchor) |
| Aggregating to a region | un_m49 (SDG regions, geographic regions) |
| Tagging a state / province / region | iso_3166_2 (universal) or us_fips / eu_nuts_2021 (jurisdiction-specific) |
| Anchoring a statistical region in EU | eu_nuts_2021 (the EU statistics convention) |
| Classifying what kind of place it is | geonames_features (city / river / mountain / etc.) |
| Anchoring an airport | icao_airport (regional grouping); use IATA codes for the specific airport (out of scope here) |
| Climate-zone tagging | koppen_climate |
| Development-finance country tier | wb_income |
Crosswalk navigation
# Translate an ISO 3166-2 subdivision to NUTS
GET /api/v1/systems/iso_3166_2/nodes/FR-IDF/translations
# Find the GeoNames feature class for a populated place
GET /api/v1/systems/geonames_features/nodes/P.PPLC
# Country profile (uses iso_3166_1 codes)
GET /api/v1/countries/US
What WoT does not host
- Postal codes (ZIP, postcode) - operational data, grows continuously, fails the "stable enumeration" test in the inclusion policy.
- Specific airport / port / station identifiers (IATA, IMO, UN/LOCODE) - operational registries, ~tens of thousands of entries each. Candidates for "World of Registries" sister product, not WoT.
- Latitude/longitude coordinate systems - notations, not classifications.
- Cadastral parcel IDs - jurisdiction-specific operational data.
Related reading
- Inclusion Policy - why postal codes and IATA are not in WoT.
- Crosswalk Map - geography is a frequent join axis.