Following World War I, in 1919, Alsace-Lorraine was returned to France under the Treaty of Versailles, and Basel was restored as a border crossing between France and Switzerland. As a consequence, the importance of Delle as a border crossing point into France became less. Transit traffic was more and more routed via Basle/St Louis. Freight traffic between Germany and Italy, which could be routed via the Lötschberg line meant that the company was able to offset the loss of transit via Delle.