district, administrative and historic county of Durham, northeastern England, located in the north-central part of the county about 12 miles (20 km) southwest of the city of Newcastle upon Tyne. Derwentside was a coal-mining area, historically important to Great Britain, encompassing an outlying section of the northeastern Pennines 400 to 1,000 feet (120 to 305 metres) high. Surface mining, often on the sides of steep hills, began in the 17th century. In the 19th and early 20th centuries mining increased with the completion of railroad lines to Newcastle upon Tyne and other nearby ports. By the late 20th century, however, coal mining had ceased, and in 1980 the steelworks at Consett closed. Former mining villages dot the countryside, but the scars of coal mining have been removed. Consett is the largest town and administrative centre. The district's other sizable town, Stanley, 6 miles (10 km) east of Consett, has textile industries. Much of the district is rural. Area 105 square miles (271 square km). Pop. (2001) 85,065.