With the globalization of social sciences, comparing national traditions is usually perceived as an epistemological and methodological issue. This challenge has been adopted for the analysis of one element of the French territorial reform, te institutionalization of the "metropole" in January 2015. The analysis is framed around a comparative perspective with the American literature on metropolitan areas (MAs). Three core questions will be addressed: How to explain the choice of such a methodology? What are the similarities and the differences between the two national contexts as expressed by their social science traditions? What can be learned about the governmentality of MAs from each national approach?