What is a city? Four ways to count the same place
Paris has 2.1 million people. Or 11 million. Or 13.3 million. All three figures are right: they count the same city at different levels. Before comparing two cities, you have to know which level each figure follows.
The four levels
- Municipality
- The city within its administrative limits. Easy to find, but the limits are historical accidents: the municipality of Paris covers 105 km², that of Marseille 240 km², so the two are not comparable.
- Urban unit
- The continuous built-up area: buildings never more than 200 m apart, whatever the limits. It is the city as you see it from a plane. France (INSEE), the United States (Census urban areas) and many statistics offices publish their own, each with its own details.
- Metro area
- The city and the towns whose workers commute to it, even across fields and forests. It measures the reach of a job market: in France, the catchment area (aire d'attraction des villes); in the United States, the metropolitan statistical area.
- Dense centre
- A satellite measure: contiguous 1 km² cells with more than 1,500 people per km² and 50,000 people in all (Global Human Settlement Layer, European Commission). The same rule everywhere on Earth, but low-density gaps can split a city.
Ten cities, four answers
| City | Municipality | Urban unit | Metro area | Dense centre |
|---|---|---|---|---|
| Paris | 2,103,778 | 11,013,774 | 13,320,752 | 9,328,385 |
| Lyon | 519,127 | 1,721,721 | 2,339,329 | 1,194,741 |
| Lille | 238,246 | 1,063,720 | 1,530,624 | 907,123 |
| New York | 8,804,190 | 19,426,449 | 19,940,274 | 14,197,659 |
| Madrid | 3,255,944 | 5,130,136 | 7,213,327 | 5,680,137 |
| Berlin | 3,426,354 | 3,756,874 | 4,582,100 | 3,549,997 |
| London | 8,961,989 | — | 13,917,244 | 10,408,332 |
| Tokyo | 9,733,276 | — | 36,271,992 | 33,155,907 |
| Brussels | 1,019,022 | 5,901,474 | 2,402,346 | 1,468,754 |
| Marseille | 886,040 | 1,648,953 | 1,917,728 | 911,934 |
Sources: France, INSEE; United States, Census Bureau; urban units elsewhere, the national statistics office where one exists, otherwise SlightlyMap from GHSL; metro areas outside France and the United States, GHSL functional urban areas; municipalities outside France, GeoNames. A dash means the level does not exist for that city in our sources.
Surprises
- Lille is small, and big. The municipality has 238,000 people, a fifth of its urban unit (1.06 million). French municipalities are small: Lille's urban unit spans dozens of them.
- Berlin barely changes. A large municipality (891 km²) that contains almost its whole built-up area: 3.4 million in the city, 3.8 million in the urban unit.
- Brussels, Antwerp and Ghent are one. In Statbel's 200 m agglomerations (2011), the built-up area runs without a break from Brussels to Antwerp and Ghent: 5.9 million people, though each city has its own metro area.
- London and Tokyo have no urban unit here. The official British built-up areas of 2022 and the Japanese densely inhabited districts both split their capitals into boroughs or wards. SlightlyMap keeps the official units as published rather than merge them on its own.
Why it matters
Most "largest city" rankings mix levels without saying so: the municipality of one city against the metro area of another. On SlightlyMap, every list says which level it follows and where its figures come from, and a game never mixes two definitions under one name. When you play Rank or Count with cities, you choose the level.
Play with these cities Open the map
More in Cities in figures: the world, France, what a city is, and one page per country.