a major industrial and coal mining region in the valley of the Ruhr river in northwestern Germany

Chief German coal-mining and industrial region, based in the valley of the River Ruhr in NW Germany. The industrial centre of the German war effort in the First World War; occupied by Belgian and French troops between 1923 and 1925, when Germany failed to keep up with its reparations payments.

The Ruhr is a medium-size river in western Germany (North Rhine-Westphalia), right tributary of the Rhine. Its source is at an elevation of approximately 2,200 feet near the town of Winterberg in the mountainous Sauerland region, and it flows into the lower Rhine river at an elevation of only 56 feet in the municipal area of Duisburg. Its total length is 217 km, its average discharge is 79 m³/s (cubic metres per second) at Mülheim near its mouth.