Tees Valley is a mayoral combined authority and Local enterprise partnership area in northern England, around the River Tees. The area is not a geographical valley. The LEP was established in 2011 and the combined authority was established in 2016, the latter after public consultation in 2015. The area covers five council areas: Darlington, Hartlepool, Middlesbrough, Redcar and Cleveland and Stockton-on-Tees. Administrating the area is the Tees Valley Combined Authority, consisting of a mayor and six selected chairs; local enterprise partnership chair and a chair for each unitary authority. The town of Middlesbrough is the largest population centre in the area. The borough of Middlesbrough is the smallest of the five at only and a population of : the Stockton-on-Tees borough (including multiple towns) is the largest with and a population of , as of Before the region, from 1968 until 1974, parts of the area had been under the County Borough of Teesside council area. This was replaced by Cleveland county, it consisted of four districts which become unitary authorities after the county was abolished in 1996. The Darlington district in the Durham county council area became a unitary authority in 1997. Background The River Tees's geographical valley is traditionally known as Teesdale. For centuries, north Tees was under the Prince-bishopric of Durham the both Darlington and Stockton had ancient wards. Middleton-st-George, Hartlepool and Billingham were in Stockton ward, the latter two were also in a district called Hartness. South Tees was under a wapentake called Langbaurgh, also known as Cleveland in Yorkshire's North Riding. Urban (such as Eston, Billingham and Saltburn and Marske by the Sea) and parts of rural districts as well as municipal (such as Stockton-on-Tees, Thornaby-on-Tees and Redcar) and county boroughs (Middlesbrough) were merged into the County Borough of Teesside in 1968. In 1974, the county borough was disbanded. During the 1974 reforms created the county of Cleveland including Hartlepool, Guisborough and other areas. Four boroughs were also created. Local government reorganisation in 1996 saw the county of Cleveland broken up with the boroughs becoming unitary authorities. The boroughs were placed into the counties of North Yorkshire and County Durham for ceremonial purposes. In 1997, the Borough of Darlington also transferred to a unitary authority structure. Governance UK Parliament Tees Valley is divided into seven and a part UK parliamentary borough constituencies: Darlington Hartlepool Middlesbrough Middlesbrough South and East Cleveland Redcar Sedgefield (shared with the