Empty diagonal

The empty diagonal (French: diagonale du vide) is a long band of French territory. Stretching from the department of the Meuse to Landes, its population density is very low, compared to the rest of France.

Description

The low population density (less than 30/mi², or 78/km²) is caused largely by the rural 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, but the latter remains the more common term and was used by DATAR.^[2]

The pattern is more readily apparent at the departmental level than at the regional level.^[3][4] It is part of a broader pattern of low population density that extends into Spain and Portugal and is known as the continental diagonal.^[5][6]

History and evolution

Before the emergence of the empty diagonal, an earlier demographic feature was the Saint-Malo-Geneva line, which divided the industrial northeast from the agrarian southwest. It was identified by Charles Dupin in his 1837 treatise Forces productives et commerciales de la France.

In 1947 the geographer Jean-François Gravier wrote of a "French desert" that corresponds, more or less, to the modern notion of the empty diagonal.

Hervé Le Bras and Emmanuel Todd argue that the concept is no longer valid in the 21st century because of growth that is observed in some departments like Indre and Gers.^[7] According to their analysis, the zone of negligible or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^[8] and that the growth observed by Le Bras and Todd is fragile and driven by a temporary influx of retirees.

Literature

La diagonale du vide is the title of a 2009 novel by Pierre Péju^[9] in which an urban businessman seeks solitude in a cottage in Ardèche.

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]

Gallery

• 
  Map of population density by department, showing the empty diagonal in blue.
• 
  Detailed map of population density, with the least populated areas in white.
• 
  A map showing population density by department. The solid line is the Le Havre-Marseille line, to the east of which lives 60% of the French population. The broken lines mark the approximate boundaries of the empty diagonal.

References