, the chief industrial region of Germany and one of the leading industrialized areas of the world. It is in North Rhine-Westphalia state, near the Dutch border and adjoining the Rhine River. The Ruhr is centered in the western part of the Ruhr River valley and extends northward to about the Lippe River, southward to the Wupper, and westward across the Rhine. The total area is about 2,000 square miles (5,180 km2). The region is intensely urbanized, especially the Ruhr valley, where large cities virtually merge with each other.
The Ruhr has immense deposits of bituminous coal. Part of the production is exported, part is used to sustain industries of the Ruhr itself.
The Ruhr is a major producer of iron and steel; few areas of comparable size can match its capacity to produce these metals. Other important industrial activities include metal-working; petroleum refining; and the making of chemicals, textiles, machinery, and electrical and transportation equipment.
Historically, the Ruhr has been so dependent on a single group of commodities—coal, iron, and steel—that its economy has tended to be unstable. Its industry is gradually becoming more diversified, however, as a result of government efforts begun in the 1960's. Efforts have also been made to reduce air pollution and clean up grime.
Cities include Düsseldorf, Wuppertal, Dortmund, Bochum, Gelsenkirchen, Duisburg, Krefeld, Mönchengladbach, and Mülheim. Essen is noted for the Krupp steel works, which supplied arms to Germany in both world wars. The cities are served by numerous railways, canals, and navigable rivers (especially the Rhine), which link them to North Sea ports in Germany and the Netherlands.
Industrial development of the Ruhr began about the middle of the 19th century, when the Krupp family enlarged their small steel mills and armament plants. Other industrialists were attracted by the abundant coal. France and Belgium occupied the strategic Ruhr, 1923-25, on the ground that Germany had not paid its World War I reparations. In World War II, Allied air raids devastated the area. After the war, when Germany was divided, it became part of West Germany. To restore West Germany's industry the Allies in 1949 permitted the Ruhr to rebuild under international control. The international authority was dissolved when the European Coal and Steel Community was set up in 1952.