Urban cluster (France)

An urban cluster ( unité urbaine in French) is a statistical area defined by the French National Institute for Statistics and Economic Studies (INSEE) that represents a contiguous area of built-up zones, with no breaks of more than 200 meters between buildings. To qualify as an urban cluster, the area must contain at least 2,000 inhabitants.

The definition focuses on the continuity of buildings rather than administrative boundaries. It is a key element in the INSEE's methodology for analyzing and categorizing the urban and rural landscapes of France. Unlike administrative units such as communes, urban clusters can straddle multiple communes, providing a more accurate representation of real urban areas.

The concept is primarily used for statistical analysis, demography, and urban planning. It allows INSEE to track population changes and urbanization trends across France. It is also used to delineate other statistical areas such as urban areas (aires urbaines) which include the urban cluster and a surrounding commuter belt.

Urban clusters are recalculated periodically, typically after each national census, to reflect changes in population distribution and built environment. The criteria and methodology are continuously refined to ensure accurate representation of France's urbanization patterns. The size and population of an urban cluster are key determinants in classifying it as either a small, medium, or large urban area.