Compared to the great rivers of the world's continents, the Thames is neither long nor mighty. Its importance comes from the great civilization that arose on its banks. Since the time of the ancient Romans, who called it the Tamesis, the Thames has been the main waterway of England.

Physical features

The Thames is about 210 miles (338 kilometers) long and runs through much of southern England. It begins in the Cotswolds, a region of limestone hills in central England. In its upper reaches, down to the town of Oxford, it is often called the River Isis. At Oxford the Thames is met by its chief western tributary, the River Cherwell. From there it flows through the English countryside and on to London. More than 40 locks break the flow of the upper river.

In its lower reaches, the river widens rapidly. At Teddington, west of central London, it is 250 feet (76 meters) wide. At London Bridge, in central London, it is 2,100 feet (640 meters) wide. And at its mouth it is 5 ¹/₂ miles (8.9 kilometers) wide. The Thames flows into the North Sea at a sandbank called The Nore in the county of Kent. Bridges and tunnels cross the river at many points.

Economy

People have lived in the Thames Valley for many thousands of years. Before the development of railways and good roads, the Thames was the area's main trade route. Over time, many industries set up shop along the banks. Water was used to power mills.

The Thames remains important to England in many ways. Houses and apartment buildings have replaced many of the factories along the river. Millions of people depend on the river for water and for sewage removal. Tourism thrives as boat rides take people past some of England's most notable sites, including Windsor Castle and the Tower of London. The Oxford-Cambridge Boat Race and the Henley Royal Regatta are rowing events that attract huge crowds. Thousands of acres by the Thames are public parklands for swimming and other recreational activities.

Environmental issues

In the first half of the 20th century, the waters of the Thames became badly polluted. A cleanup effort in the 1960s helped to improve the water's quality. As a result, the Thames has come to support more than 100 different kinds of fish and a large number of other water creatures.

In the past, high tides on the North Sea have triggered floods on the lower reaches of the Thames. The Thames Barrier, completed at Woolwich in 1982, consists of massive floodgates that can be closed when tides are high.