Ruhr

River in Germany, length 235 km/146 mi. It rises in the Rothaargebirge Mountains at the eastern boundary of North Rhine-Westphalia, and flows west, past Witten, Essen, and Mülheim, to join the Rhine at Duisburg. The Ruhr Valley, a metropolitan industrial area, produces petrochemicals, cars, iron, and steel at Duisburg and Dortmund; it is the principal manufacturing centre of Germany and formerly known as one of the world's leading industrial complexes. In the 1980s the coal and steel industries declined, leading to serious unemployment.

The area was occupied by French and Belgian troops 1923–25 in an unsuccessful attempt to force Germany to pay reparations laid down in the Treaty of Versailles. During World War II the Ruhr district was severely bombed as it was vital to German industry. The seven dams across the river were constantly bombed by the Allies in an attempt to flood the area (for example, with the ‘bouncing bombs’), although without success. Allied control of the area from 1945 came to an end with the establishment of the European Coal and Steel Community in 1952. Control of the region passed to West Germany in 1954.