County Borough of Teesside councils in 1918, and was a pioneer operator of electric trolleybuses. The three undertakings adopted a common livery of turquoise and cream in 1967 in preparation for their amalgamation. On 1 April 1968 the combined fleet became Teesside Municipal Transport. Teesside initially operated a mixed fleet of trolleybuses and omnibuses, but on 4 April 1971 trolleybus operation ended. A formal closure ceremony was held two weeks later. Before 1968 the Teesside area was served by three police forces: Middlesbrough Borough Police, Durham Constabulary and the North Riding of Yorkshire Constabulary. It was originally envisaged that the new county borough would
Teesside the 2001 figure of 18,335. Infilling development may join the two urban areas together. Marske-by-the-Sea is another separate Urban Area nearly contiguous with Redcar with a population of 8,282 down 7% from the 2001 figure of 8,921. Nearby Hartlepool is also sometimes considered as part of Teesside. The Hartlepool area has an urban population of 88,855 an increase of 3% from the 2001 figure of 86,085 and this can be referred to as the Teesside & Hartlepool Urban Area. If this definition is taken into consideration, with the addition of the Eaglescliffe area and Marske, Teesside would have a population