Districts of Wales in the context of "Principal areas of Wales"

The Local Government Act 1972 (c. 70) is an act of the Parliament of the United Kingdom that reformed local government in England and Wales on 1 April 1974. It was one of the most significant acts of Parliament to be passed by the Heath Government of 1970–74.

The act took the total number of councils in England from 1,245 to 412 (excluding parish councils), and in Wales to 45. Its pattern of two-tier metropolitan and non-metropolitan county and district councils remains in use today in large parts of England, although the metropolitan county councils were abolished in 1986, and both county and district councils have been replaced with unitary authorities in many areas since the 1990s. In Wales, too, the Act established a similar pattern of counties and districts, but these have since been entirely replaced with a system of unitary authorities.

Montgomeryshire (Welsh: Sir Drefaldwyn 'the shire of Baldwin's town', or simply Maldwyn) was one of the thirteen counties of Wales that existed from 1536 until their abolition in 1974, later becoming a district of Powys from 1974 to 1996. It was named after its county town, Montgomery, which in turn was named after one of William the Conqueror's main counsellors, Roger de Montgomerie, who was the 1st Earl of Shrewsbury.

The area of what was Montgomeryshire, now constitutes the northern part of the county of Powys. The current area was 2,174 square km (839 square miles).

South Pembrokeshire (Welsh: De Sir Benfro) was one of six local government districts of Dyfed, Wales from 1974 to 1996.

The Local Government (Wales) Act 1994 (c. 19) is an Act of the Parliament of the United Kingdom which amended the Local Government Act 1972 to create the current local government structure in Wales of 22 unitary authority areas, referred to as principal areas in the Act, and abolished the previous two-tier structure of counties and districts. It came into effect on 1 April 1996.