Unlike other canals, the Forth and Clyde kept going into the 20th century. A popular fleet of pleasure steamers - Fairy Queen, May Queen and Gipsy Queen I - took city folk into the country to enjoy fresh air and greenery. Cargo operations too carried on strongly, but were dealt a mortal blow when the First World War began. The ports of the upper Forth were closed to commercial shipping so that access to Grangemouth, the canal's principal point of import and export, was forbidden. Trade left the canal and went onto rail and road. It never returned. After the War, road traffic began to increase and some of the old iron and wood canal bridges were replaced with steel swing and lifting bridges. Two of the biggest were built in Glasgow in the 1930s at Cloberhill on Great Western Road and at Temple on Bearsden Road. A smaller bridge was erected at Lambhill in 1935.
During the Second World War the boatyard at Kelvin Dock, Maryhill, was kept busy building landing craft. Maryhill suffered during air raids on the city too, but although the canal there sustained no damage it was breached by a bomb near Great Western Road and at Clydebank during the heavy raids there.
After the War, the Monkland Canal, which had been moribund since the 1930s, was closed and the Forth and Clyde became seen as an anachronism. Trade dwindled to almost nothing and the principal traffic was East Coast fishing boats moving to new grounds on the west coast.