In 1974 Durham was divided between three counties. The boroughs of Hartlepool and Stockton-on-Tees became a part of the new non-metropolitan county of Cleveland. The metropolitan county of Tyne and Wear became responsible for Gateshead, Sunderland and South Tyneside. The new non-metropolitan county of Durham also covered the former area of Startforth Rural District, a part of the historic North Riding of Yorkshire, and south of the historical boundary of the River Tees.