mirkokiefer/city-slugs

City Slugs

Two canonical, URL-safe identifiers for each of 234,136 cities and towns worldwide (every GeoNames populated place with population ≥ 500), fixed by a deterministic rule:

• id — the short, recognizable form: ber, sf, nyc, tyo for cities with a curated metro / airport / colloquial code; equal to the slug otherwise.
• slug — the written-out form: berlin, sanfrancisco, newyorkcity.

Both are globally unique and resolve to the same city. Geocoding ids (GeoNames ids, place ids) are stable but opaque; names are readable but ambiguous (there are six Heidelbergs). This dataset gives each place a single readable identifier that survives in a URL, a config file, or a conversation.

Schema

column	type	notes
id	string	short canonical id (ber); equals slug when no curated short form
slug	string	written-out canonical slug (berlin)
name	string	display name
country	string	ISO 3166-1 alpha-2
region	string | null	GeoNames admin-1 name, present where it disambiguates
timezone	string	IANA zone
lat, lng	float	coordinates, rounded to 2 decimals (~1 km)
population	int	GeoNames population

id   slug          name             country  population
ber  berlin        Berlin           DE        3644826
sf   sanfrancisco  San Francisco    US         864816
nyc  newyorkcity   New York City    US        8804190
—    heidelberg    Heidelberg       DE         160355
—    paloalto      Palo Alto        US          66853

Assignment rules

Slugs are claimed in global population order; each city takes the shortest free form: name → name_cc → name_cc_region → name_cc_region_N. The bare name goes to the most populous bearer (paloalto = Palo Alto, California), namesakes fall to the disambiguated forms (paloalto_mx).

Ids equal the slug unless a curated short form exists, claimed over the same namespace (so an id never collides with another city's slug): colloquial name (sf) → metro code (nyc) → iconic airport code (ber, curated allow-list — cryptic codes like bom/msy stay search aliases) → else id = slug.

Deterministic: the same GeoNames snapshot yields the same assignment. Treat published ids and slugs as append-only.

Usage

from datasets import load_dataset
ds = load_dataset("mirkokiefer/city-slugs", split="train")
ds.filter(lambda r: r["country"] == "DE" and r["population"] > 50000)

import duckdb
duckdb.sql("SELECT id, slug, name FROM 'city-slugs.parquet' WHERE id != slug LIMIT 10")

Provenance & license

Derived from GeoNames (cities500 + admin1CodesASCII), CC BY 4.0; this dataset is published under the same license.

Also available as an npm package (city-slugs, with JSON tiers + a byId / bySlug API) and on GitHub. Born in Zeit — a world clock for iPhone, Mac, and the web, where the ids power short share URLs (zeit.xyz/?c=ber,sf,nyc).