Teesside the four independent unitary authority boroughs of Hartlepool, Stockton, Middlesbrough and Redcar and Cleveland (a renamed Langbaurgh). At this time they were returned to the counties of North Yorkshire and County Durham for ceremonial purposes, with Stockton-on-Tees becoming the only district in England split between two ceremonial counties. In 1998 the neighbouring Borough of Darlington also became an independent unitary authority and this along with the four former Cleveland boroughs form the sub-region of the Tees Valley which is used for statistical purposes and governmental organisation. The name Tees Valley is increasingly promoted for economic and cultural connections, though Teesside,
County Borough of Teesside County Borough of Teesside Teesside was, from 1968 to 1974, a local government district in northern England. It comprised a conurbation that spanned both sides of the River Tees from which it took its name. The district had the status of a county borough and so was independent of the County Councils of the North Riding of Yorkshire and of County Durham, in which it was geographically located. The River Tees formed the historic county boundary between Yorkshire and Durham. A continuous conurbation had built up around the mouth of the river, increasing greatly in population from the nineteenth century