Identifying "cities" of the world: a methodological approach, lexicon, and database for urban administrative units.

Since 2015, there has not been a comprehensive database of cities across the world. While debates about what defines a "city" remain open in urban science, we center our efforts toward developing a replicable and transparent methodology to construct a globally valid dataset of cities, agglomerations, capitals, municipalities, and urban centers. Such an endeavor is both timely and necessary given that comparative research, governmental collaborations, and cross-national comparisons among urban areas yield valuable knowledge about human settlements to inform climate resilience and sustainability planning. Our approach is bottom-up and anchored in accessibility. We begin with Wikipedia, a dynamic, crowd-sourced platform, and cross-check its entries with an expert database based on census data. When discrepancies arise, we turn to official governmental websites to confirm information. We integrate these three sources into a harmonized database that includes every urban settlement worldwide with at least 50,000 residents (7,468 in total). For China, Brazil, France, Japan, India, Pakistan, Somalia and North Korea we apply a higher inclusion threshold of 100,000. Each entry lists country and city names and is complemented by a terminology lexicon explaining how different nations define and classify cities. This approach enables us to not only catalogue urban settlements but also to make visible how cities are constructed and recognized within diverse global national governance frameworks.