The term "metropolitan borough" was first used for administrative subdivisions of the County of London between 1900 and 1965. However, the present boroughs of Greater London, which have different boundaries and functions, and are much larger in area, are known as London Boroughs rather than metropolitan boroughs.
The current metropolitan boroughs were created in 1974 as subdivisions of the new metropolitan counties, created to cover the six largest urban areas in England outside Greater London. The new districts replaced the previous system of county boroughs, municipal boroughs, urban and rural districts. The districts typically have populations of 174,000 to 1.1 million.
Metropolitan districts were originally parts of a two-tier structure of local government, and shared power with the metropolitan county councils (MCCs). They differed from non-metropolitan districts in the division of powers between district and county councils. Metropolitan districts were local education authorities, and were also responsible for social services and libraries, but in non-metropolitan counties these services were the responsibility of county councils.
In 1986, the metropolitan county councils were abolished under the Local Government Act 1985 and most of their functions were devolved to the metropolitan boroughs, making them, to a large extent, unitary authorities in all but name. At the same time, however, some of the functions of the abolished metropolitan county councils were taken over by joint bodies such as passenger transport authorities, and joint fire, police and waste disposal authorities.
The metropolitan districts are administered by metropolitan district councils. They are the principal local authorities in the six metropolitan counties and are responsible for running most local services, such as schools, social services, waste collection and roads.