This work aims to examine the process of centralization that took place in France between 1870 (major decentralization laws at the beginning of the Third Republic) and 1970 (the height of a more Jacobin Fifth Republic). In the space of barely a century, local authorities have gone from being new democratic forces, some of which offered a potential political alternative to the central state, to playing a supporting role, attempting to resist the centralization movement that has been gaining ground since the interwar period. This simple observation, born of the confrontation between two key dates that mark an important sequence in the construction of the French political and administrative system in the 20th century, is at the origin and heart of the reflection carried out in this HDR thesis. It focuses on the study of intergovernmental dynamics from 1870 to the early 1970s and what can be considered the slow "closure" of the institutional game that had been opened by the Third Republic. This process has ultimately been little studied in the long term and in all its complexity, both by historians and political scientists. It is often attributed to a vague movement of "nationalization" and "centralization," which is usually associated with the regime changes that affected France (the transition from the Third to the Fifth Republic), to a general context favorable to the state (world wars, the economic crisis of the 1930s, reconstruction and modernization), and the establishment of a functional social organization at the expense of territorial structuring. Without dismissing these broad but overly simplistic explanations, the aim here is to take a closer look at this process of reshaping intergovernmental relations, questioning the sometimes paradoxical role that local authorities may have played in it.
To this end, the thesis draws on an original manuscript, the subject of the second volume, entitled "Electricity and local authorities in France (1880-1980). Another history of public service." Capitalizing on several personal research projects, it offers a new interpretation of the formation of the French model of public electricity service, starting not from the state and the various actors or institutions that comprise it, but from local authorities, which played an important, albeit little-known, role in the centralization process. Volume 1 compares this unique history with other public policy trajectories (social action, hygiene and health, urban planning, etc.) to renew the classic historiographical interpretation of the evolution of the French political and administrative system during the 20th century. It defends the hypothesis of a two-sided centralization, an expression of Jacobinism that was both "tamed" by local authorities (the traditional thesis of political scientists and historians) but also "tamed" them (a new perspective highlighted in volumes 1 and 2), then outlines some programmatic areas of research.