12 pages; International audience; Since few decades, the politicians' analysis used the prosopographical method. Thanks to the social networks' analysis assets, concerning a long period (1800-1940) we bring the proofs, that the Third French Republic (1871-1940) hasn't been the theatre of a renewal of local and national political elites. Therefore, we have taken reference from the concept of Sippe created by medieval historians. Our research is a new and integral analysis from the French local politicians in a local and electoral space. The most convincing results, stemming from this method of analysis, are little of renewal of the political elite under the Third Republic and the importance of the seizure of the local politics. Indeed, the local and departmental political space is put under guardianship by some allied families from which we can bring out a departmental Sippe which controls a great majority of seats and mandates within the framework of this republican system and leaning on a family tradition anchored for a long time. That's why we can highlight a dichotomy between the spirit, the letter and the reality of the republican and democratic political space; this one opens the multitude of candidates' possibilities but the reality of this opening is really tiny. The objective of our communication thus is to emphasize both the method used in this research and the main obtained results.