BLYTH, municipal borough and seaport of Northumberland, England, at the mouth of the river Blyth, on a branch of the L.N.E. railway. Pop. (1931) 31,8o8. This is the port for a consid erable coal-mining district, and its harbour, on the south side of the river, is provided with mechanical appliances for shipping coal. There are five dry docks, and upwards of 1 gym. of quayage. Timber is largely imported. Some shipbuilding and the manufacture of rope, sails and ship-fittings are carried on, and the fisheries are valuable. A municipal borough since 1922, Blyth is governed by a mayor and corporation of 4o members. Area, 4,312 acres. It is included in the parliamentary borough of Morpeth.