The river's position has put it at the centre of many events in British history, leading to it being described by John Burns as "liquid history".
Two broad canals link the river to other river basins: the Kennet and Avon Canal (Reading to Bath) and the Grand Union Canal (London to the Midlands).
The Thames is the longest river entirely in England, but the River Severn, which is partly in Wales, is the longest river in the United Kingdom.As the River Churn, sourced at Seven Springs, is 14 miles (23 km) longer than the Thames (from its traditional source at Thames Head to the confluence), the overall length of the Thames measured from Seven Springs, 229 miles (369 km), is greater than the Severn's length 220 miles (350 km).The administrative powers of the Thames Conservancy have been taken on with modifications by the Environment Agency and, in respect of the Tideway part of the river, such powers are split between the agency and the Port of London Authority.In non-administrative use, stemming directly from the river and its name are Thames Valley University, Thames Water, Thames Television productions, Thames & Hudson publishing, Thameslink (north-south railways passing through central London) and South Thames College.It rises at Thames Head in Gloucestershire, and flows into the North Sea via the Thames Estuary. Its tidal section, reaching up to Teddington Lock, includes most of its London stretch and has a rise and fall of 7 metres (23 ft).
Running through some of the driest parts of mainland Britain and heavily abstracted for drinking water, the Thames' discharge is low considering its length and breadth: the Severn has a discharge almost twice as large on average despite having a smaller drainage basin.
These include a variety of structures connected with use of the river, such as navigations, bridges and watermills, as well as prehistoric burial mounds.
A major maritime route is formed for much of its length for shipping and supplies: through the Port of London for international trade, internally along its length and by its connection to the British canal system.
The river gives its name to three informal areas: the Thames Valley, a region of England around the river between Oxford and West London; the Thames Gateway; and the greatly overlapping Thames Estuary around the tidal Thames to the east of London and including the waterway itself.
Thames Valley Police is a formal body that takes its name from the river, covering three counties.
It also flows through Oxford (where it is called Isis), Reading, Henley-on-Thames and Windsor.