Cities were defined territorially in terms of metropolitan areas, for which official criteria were used together with academic studies and other inputs. The territorial definition used is identical for the two censuses, meaning that there is intercensal comparability, at least on the MIAD scale. This finding may be surprising, given the increasing prominence of the issue on the public agenda (although the region's specialized literature does not treat it as so much of an oddity), besides which it can be questioned methodologically, owing to the shifting proportions of the groups involved in the analysis.