Our thesis investigates the expansion of urban traffic from the early 1910s to the late 1960s. Initially built around the case of Lyon, one of the major French cities nowadays, the study also refers to the situation of others places -namely Marseille, Lille, Bordeaux, Nice, Saint-Etienne and Villeurbanne- in order to further underline the specificities -or lack of- of the city of Lyon. Not only does it rely on municipal archives, but also on national and international archives and periodicals issued by either public authorities or private bodies. Two main themes of interest structure the dissertation: the social construction of a public problem and the related regulation of public intervention. We investigate them through the study of local, as well as national and international, debates over the place of the car in the city. By focusing more precisely on urban governance, we shed light on a « government by commissions » that creates spaces for the co-production of expertise and public intervention by various public and private actors otherwise isolated. Most interestingly, we found that both the topic –how to accommodate the car in the city- and its means of governance –which implication should follow from private as well as public actors- structured progressively through the twentieth century. The study of transportation thus works as a great lens to observe and analyze the reshaping of urban government around the themes of empowerment and governance, at the very heart of political science and public policy analysis.