Portland is an ancient royal manor, and until the 19th century remained a separate liberty within Dorset for administration purposes. It was then an urban district from 1894 to 1974. The borough of Weymouth and Portland formed on 1 April 1974 under the Local Government Act 1972 by merger of Portland urban district with the borough of Weymouth and Melcombe Regis. In 2020, the borough of Weymouth of Portland was abolished when Dorset moved to a unitary authority structure of local government.