Readers love lists, especially city rankings. There are lists that rank the world’s leading cities of opportunity, the most sustainable cities, the bike-friendliest cities, the top shopping cities, and even the most competitive cities in the future. What they all share is an attempt to measure cities. But what defines a city? The answer isn’t as clear-cut as it seems.
Every year, leading corporations fund the publication of an increasingly large number of benchmarking studies, which generate significant interest in the media. Even the UN has jumped on this bandwagon by adapting, for the first time, an urban goal within the Sustainable Development Goals framework. However, the basic question of what constitutes a city is often defined inconsistently across rankings. This could leave general-interest readers and policymakers, confused, or worse—misled.
The debate on how to define a city is not new. National census bureaus, international organizations, and independent researchers have all developed carrying definitions based on their unique perspectives. Readers must always be consciously aware of the specific unit of analysis underlying each ranking before deciding whether City A is more sustainable or competitive than City B.
The Economist Intelligence Unit’s Hot Spots 2025 report for instance defines a city as “the urban agglomeration or metropolitan area it holds together,” which has neither administrative nor functional reference. One may argue that a city is “held together” by its public transport network, commuting patterns, the density of its population, or even support for its local sports teams.
