The empty diagonal (French: diagonale du vide) is a band of low-density population that stretches from the French department of the Landes in the southwest to the Meuse in the northeast. The diagonal's population density is very low compared to the rest of France.
The low population density (less than 30/km², or 78/mi²) is caused largely by the rural exodus and urbanisation of the 19th and 20th centuries. Some commentators prefer to speak of a "low-density diagonal" (diagonale des faibles densités) and regard the term "empty diagonal" as both pejorative and exaggerated. Still, DATAR used the term and it remains the more common term.
The pattern is more readily apparent at the departmental level than at the regional level. It is part of a broader pattern of low population density that extends into Spain and Portugal and is known as the continental diagonal.
History and evolution
Before the emergence of the empty diagonal, an earlier demographic feature was the Saint-Malo-Geneva line that ran from the northwest to the southeast and divided the industrial northeast from the agrarian southwest. Charles Dupin identified it in his 1837 treatise Forces productives et commerciales de la France.
Hervé Le Bras and Emmanuel Todd argue that the concept is no longer valid in the 21st century because of growth that is observed in some departments like Indre and Gers. According to their analysis, the zone of negligible or negative population growth extends is only from the Massif Central to Lorraine. However, an analysis at the level of cantons and communes indicates that the zone of decline extends beyond the Massif-Lorraine axis and that the growth observed by Le Bras and Todd is fragile and driven by a temporary influx of retirees.
From 2015 to 2016, the author and blogger Mathieu Mouillet spent 18 months exploring the empty diagonal and meeting its inhabitants. His "exotic voyage" is presented by notes and photographs on his blog.
- Jean-Claude Bontron (1976). La France des faibles densités, II : Documentation bibliographique, Analyses d'études. SEGESA-ACEAR.
- Gilles Fumey (2009-10-26). "La France en diagonales" (PDF). Retrieved 18 July 2016..
- "Le Massif Central: au coeur de la diagonale du vide".
- "La France : des territoires en mutation".
- Rozenblat, C. "Tissu d'un semi de villes européennes" (PDF).
- Yoann Doignon, Sébastien Oliveau, Isabelle Blöss-Widmer. "L'Europe méridionale depuis 20 ans : dépeuplement, dépopulation et renouveau démographique".CS1 maint: Multiple names: authors list (link)
- Hervé Le Bras, Emmanuel Todd, Le Mystère français, seuil, 2013
- Yoann Doignon, Sébastien Oliveau (20 January 2016). "La diagonale se vide ? Analyse spatiale exploratoire des décroissances démographiques en France métropolitaine depuis 50 ans".
- La diagonale du vide, ISBN 9782070781034, Éditions Gallimard, Collection Blanche
- "La diagonale du vide".