Northumberland (nôrthŭmˈbərlənd) [key], county (1991 pop. 300,600), 2,019 sq mi (5,229 sq km), NE England; administratively, Northumberland is a unitary authority (since 2009). Northernmost of the English counties, it is separated from Scotland by the Cheviot Hills and the Tweed River, and borders on the North Sea. The terrain is level along the rugged coast line and hilly in the interior, where high moorlands alternate with fertile valleys. Other rivers are the Tyne, the Derwent, the Wansbeck, the Till, the Alno, and the Coquet. In the past the economy was dominated by coal mining, shipping, shipbuilding and repairing, and the production of heavy electrical machinery, but these have suffered a heavy decline. Sheep and cattle are raised.
Hadrian's Wall was built in Roman times. In the 6th cent. the Angles established themselves in the region, which later became the kingdom of Northumbria. The area suffered severely during the border wars between England and Scotland. In 1974, Northumberland was reorganized as a nonmetropolitan county; the small but populous and industrialized southeast (including Newcastle upon Tyne) became part of the metropolitan county of Tyne and Wear (abolished as a unit of local government in 1986).