RUNCORN, a market town and river-port in the Northwich parliamentary division of Cheshire, England, on the S. of the estuary of the Mersey 16 m. above Liverpool. Pop. of urban district (1901) 16,491. It is served by the London & North-Western railway, and has extensive communications by canal. The modern prosperity of the town dates from the completion in 1773 of the Bridgewater Canal, which here descends into the Mersey by a flight of locks. Runcorn is a sub-port of Manchester, with which it is connected by the Manchester Ship Canal, and has extensive wharfage and warehouse accommodation. The chief exports are coal, salt and pitch; but there is also a large traffic in potters' materials. A transporter bridge between Runcorn and Widnes, with a suspended car worked by electricity to convey passengers and vehicles (the first bridge of the kind in England) was constructed in 1902. The town possesses shipbuilding yards, iron foundries, rope works, tanneries, and soap and alkali works.
Owing to the Mersey being here fordable at low water, Runcorn was in early times of considerable military importance. On a rock which formerly jutted into the Mersey Æthelfleda erected a castle in 916, but of the building there are now no remains; while the rock was removed to further the cutting of the ship canal. Æthelfleda is also said to have founded a town, but it is not noticed in Domesday. The ferry is noticed in a charter in the 12th century.