Eurostat, the European Union's statistical agency, has created the concept of Larger Urban Zone (LUZ) in an effort to harmonise definitions of urbanisation in the European Union and in countries outside the European Union. These definitions were agreed between Eurostat and the National Statistics Offices of the different countries of the European Union at the European Commission's Urban Audit of 2004. LUZs have been criticised for their insufficient harmonisation of data, which are still collected by national governments within local administrative units, making it sometimes difficult to compare LUZs from different countries. In 2006, about a third of the LUZ definitions were changed, significantly improving the comparability of LUZ definitions across different countries. Several cities, such as Marseille, Lille and Nice, are excluded by definition from the list of LUZs on technical, definitional grounds, such as the coincidence of the metropolitan area with the urban zone.

Les LUZ (Larger Urban Zones), en français Zones urbaines élargies, sont des créations de l'Audit Urbain de la Commission européenne pour permettre de meilleures comparaisons internationales. En effet les CMSA des États-Unis regroupent de plus larges superficies et populations que par exemple les  unités urbaines françaises.