In 50AD, the Egyptian mathematician, astronomer and geographer Claudius Ptolemy wrote of the river as "Klōta",[7] It was called Clut or Clud by the Britons and Clota by the Romans.

The goddess's name in turn derives from an older, Proto-Celtic word meaning 'the strongly flowing one' or 'the holy cleanser'.

[10] Permanent settlements and structures, including what is believed to be a temple to moon gods in Govan, were constructed in the area during the Neolithic and Bronze Ages.

Before the legions of the Roman Empire arrived in southern Scotland, the river and the area surrounding it had been settled by the Brythonic-speaking Damnonii tribe.

Therefore the Roman legions and Damnonii tribespeople are assumed to have been on good terms and to have co-operated by means of trade and the exchange of military information.

The kingdom was ruled from its original capital, the near impenetrable Alt Clut fortress (Dumbarton Rock), which was situated on the river and overlooked much of the estuary.

It was also a reservoir of native Welsh culture: Its territory expanded along the Clyde Vae Southern Uplands and Ayrshire, and eventually southwards into Cumbria.

In the 7th century, Saint Mungo established a new Christian community on the banks of the Clyde, potentially replacing Cathures if this is assumed to have occupied the same locus.

Several villages along the Clyde that were founded in or before this period have endured to this day, and have grown to become towns, including Llanerc (Lanark), Cadzow (Hamilton), and Rhynfrwd (Renfrew).

The Southern Upland Way crosses both streams before they meet at Watermeetings (grid reference NS953131) to form the River Clyde proper.

[13] Over three centuries the river has been engineered and widened where it passes through Glasgow city centre and onwards towards Dumbarton and Greenock and the open sea.

[14] The economic prosperity that the Clyde made possible at the beginning of the Industrial Revolution was due to the location of Glasgow, as a port facing the Americas.

In 1768, John Golborne advised that the river should be made narrower and the scour increased by constructing rubble jetties and dredging sandbanks and shoals.

This turned out to be insufficient to solve the problem, so in 1773, a training wall called the Lang Dyke was built on the Dumbuck shoal to stop water flowing over into the southern channel of the river.

In the late 18th and early 19th centuries, hundreds of jetties were built out from the banks of the river between Dumbuck and the Broomielaw quay in Glasgow proper.

Around this time, the Clyde became an important source of inspiration for artists, such as John Atkinson Grimshaw and James Kay,[19] who were interested in painting scenes that depicted the new industrial era and the modern world.

The completion of the dredging was well-timed, because the channel finally became navigable all the way from Greenock to Glasgow just when the steelwork industry had begun to grow in the city.

The term Clydebuilt became an industry symbol of high quality, and the river's shipyards were given contracts to build prestigious ocean-going liners, as well as warships.

These included, among many others, John Brown & Company of Clydebank, Denny of Dumbarton, Scott of Greenock, Lithgows of Port Glasgow, Simon and Lobnitz of Renfrew, Alexander Stephen & Sons of Linthouse, Fairfield of Govan, Inglis of Pointhouse, Barclay Curle of Whiteinch, Connell and Yarrow of Scotstoun.

The Clyde became famous worldwide for its significant contribution to yachting and yachtbuilding, and was the home of many notable designers: William Fife III, Alfred Mylne, G. L. Watson, E. McGruer, and David Boyd.

More than 55 boats were built by Robertson's in preparation for World War I, and the yard remained busy even during the Great Depression in the 1930s, as many wealthy businessmen developed a passion for yacht racing on the Clyde.

After the war, the yard built the successful one-class Loch Longs and two 12 m (39 ft) challengers for the America's Cup, designed by David Boyd: Sceptre (1958)[21] and Sovereign (1964).

Because of difficult business conditions in 1965, the yard turned to doing GRP production work (mainly building Pipers and Etchells), and it closed in 1980.

In the immediate postwar period, the sharp reduction in warship orders was initially balanced by a prolonged boom in merchant shipbuilding.

Several Clydeside yards booked a series of loss-making contracts in the hope of weathering the storm, but their unprofitable circumstances continued for too long, and by the mid-1960s they faced potential collapse.

The Clyde Waterfront Regeneration project from 2008 aims to continue this approach of finding new uses and attracting new investment, from Glasgow Green to Dumbarton.

The sediments showed a long but declining history of coal usage and, beginning around the 1950s, an increasing reliance on petroleum fuels.

[29] The Polmadie Burn, which flows into the Clyde at Richmond Park, remains heavily contaminated by hexavalent chromium, to the extent it turned bright green in 2019,[31] and yellow in 2021.

[30] The amounts of 16 polybrominated diphenyl ether (PBDE) compounds used as flame retardants in televisions, computers, and furniture upholstery were measured in sediment cores collected from six sites between Princes Dock and Greenock.

[citation needed] In 2020, West Dunbartonshire Council deployed a river source heat pump scheme in the area called Queens Quay.