[1] The canal was such a success that the locks had to be duplicated throughout in the early 20th century, at the same time deepening the channel, enlarging the tunnels, and increasing water supplies.

Later improvements included electric barge traction on rails, installed during World War I, mechanising locks, and providing public lighting on the busiest sections.

[1] The Canal in World War I formed part of the Hindenburg Line, a German defensive position built during the winter of 1916–1917.

The Allied crossing of the St Quentin Canal in 1918 was a significant part of the Hundred Days Offensive that led to the Armistice.

Commercial traffic declined after opening of the Canal du Nord, and it is now consistently quiet and peaceful, although a few Freycinet barges still use this route.