"Territorial authority" is the generic term used for local government entities in New Zealand.
The Local Government Act 1974 began the process of bringing urban, mixed, and rural councils into the same legislative framework.
Substantial reorganisations under that Act resulted in a shake-up in 1989, which abolished all the counties except for the Chatham Islands County, which survived under that name for a further 6 years but then became a "Territory" under the "Chatham Islands Council".
As part of the restructuring, many provincial cities were combined with surrounding rural counties to form districts.
For example, Hastings became a district, although its population is greater than nearby city Napier, which did not acquire any rural areas.
The numerous borough and county councils were amalgamated into larger districts, while the number of cities was reduced.
Nelson-Marlborough Regional Council was disestablished in 1992, when its functions went to the unitary authorities Nelson, Tasman, and Marlborough.
Banks Peninsula District is an exception; it was merged into Christchurch City Council in 2006.