Industrialisation and deindustrialisation (19th–20th centuries)
The Industrial Revolution in the second half of the 19th century caused a gradual decline in the activity of the saltworks in the Seille valley, the last of which closed in 1945. New ways of extracting and using salt were being developed in the Nancy basin, around thirty kilometres from the Seille valley, with the mines in Varangéville and the chemical industry in Dombasle-sur-Meurthe (Meurthe-et-Moselle).
The events of the Second World War caused major destruction, like that seen in Moyenvic and Marsal. The position of Côte Saint-Jean in Moyenvic was the scene of fierce fighting in November 1944, at the time of the American advance into the territories of Alsace-Moselle, which had been annexed by Nazi Germany. The post-war period has left many examples of Reconstruction architecture, particularly in Moyenvic.
The Seille valley today
In the second half of the 20th century, the industrialisation of farming practices, combined with the spread of urbanised areas, meant that the Seille valley no longer played the major economic and cultural role it traditionally had, at least since Celtic times.
With its exceptional archaeological heritage, which has been relatively untouched by development work, the upper Seille valley is now a unique repository of the history of salt, from its distant prehistoric origins right up to the modern period.
