The beginning of the twenty-first century has brought about multiple changes for French ports, such as increased competition and the loss of market share, as well as reforms that have reorganized the national port system. In this context, France's western coastline constitutes a major stake for the development of the country's foreign trade. Indeed, it is located in an ambivalent position, both closely connected to and at the same time competing with the Northern-Range. Since the large port reform of 2008, the three autonomous ports of France's western coast (Dunkirk, Le Havre, and Nantes-Saint-Nazaire) have become "Large Maritime Ports" (Grands ports maritimes), or "major seaports" in English. If their institutional governance subscribes to a general model, we can nevertheless observe local specificities which are reinforced by the contemporary merging of the ports of the Seine Axis (Le Havre, Rouen and Paris).Beyond the institutional dimension, therefore, the paper will analyse the decision-making mechanism and structuring of local leaderships according to the representations of the main stakeholders of the three port cities. For this purpose, the representatives of the stakeholders involved were interviewed during a series of consultations, aiming at defining the urban port governance processes in each territory. Thus, the articulation of the scales of power, private-public relations, opposition between port workers' unions, port authorities or organizations defending the interests of industrial port companies, are expressed through nuances that give substance to port dynamics, as complex as it is subtle.