Theempty diagonal (French:diagonale du vide) is a band of low-density population that stretches from theFrench department of theLandes in the southwest to theMeuse in the northeast. The diagonal'spopulation density is very low compared to the rest of France.
The low population density (less than 30/km2 or 78/sq mi) is caused largely by therural exodus and urbanisation of the 19th and 20th centuries. Some commentators[1] 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[2] used the term and it remains the most common term.
The pattern is more readily apparent at thedepartmental level than at theregional level.[3][4] It is part of a broader pattern of low population density that extends intoSpain andPortugal and is known as thecontinental diagonal [es].[5][6]
Before the emergence of the empty diagonal, an earlier demographic feature was theSaint-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 treatiseForces productives et commerciales de la France.[citation needed]
In 1947, the geographerJean-François Gravier wrote of a "French desert" that corresponds, more or less, to the modern notion of the empty diagonal.[citation needed]
Hervé Le Bras andEmmanuel Todd argue that the concept is no longer valid in the 21st century because of growth that is observed in some departments likeIndre andGers.[7] According to their analysis, the zone of negligible or negative population growth extends only from theMassif Central toLorraine. However, an analysis at the level of cantons and communes indicates that the zone of decline extends beyond the Massif–Lorraine axis[8] and that the growth observed by Le Bras and Todd is fragile and driven by a temporary influx of retirees.[citation needed]
La diagonale du vide is the title of a 2009 novel byPierre Péju[9] in which an urban businessman seeks solitude in a cottage inArdèche.
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.[10]
