This article originally appeared on VICE France.
For decades, residents of small towns across Europe have been leaving the countryside in their droves and moving to cities for jobs, more resources and better opportunities. The countryside, therefore, is emptying out. Few places represent this better than the least populated area in France – the so-called "diagonale du vide" (the empty diagonal).
The 900-mile-long region stretches across France, from the Meuse river in the north-east to the Pyrenees in the south-west, and only has a population density of 78 people per square mile. For comparison, Paris has a population density of around 54,000 people per square mile.
After living in Paris for a decade, photographer Mathieu Mouillet decided it was time to explore the rest of the country. So, in May of 2015, he began an 18-month-long trip across the empty diagonal on foot, bicycle and even hot-air balloon, documenting his journey along the way.
Mouillet has now turned his project into a book, La Diagonale Du Vide - Un Voyage Exotique en France, which he hopes captures the people and views that make up this deserted space.
Scroll down to see more photos from Mouillet's book.