The Local Government Act (1974), with subsequent modifications, substantially changed the structure of local government in New Zealand. The previous system was based on territorial local authorities: boroughs, which served concentrated populations of at least 1,500; counties, which were predominantly rural; and town districts, an intermediate form. In addition, there were special-purpose authorities to administer harbors, hospitals, electricity and water distribution, and other public services. The 1974 legislation added two tiers to this structure. Regional bodies—including united councils, which are appointed by the constituent territorial authorities in a region, and regional councils, which are directly elected—are charged with two mandatory functions, regional planning and self-defense, and may undertake other regional functions. Moreover, within territorial local authorities, communities may be established. Each community may have either a district community council (if the population is 1,500 or more), which exercises nearly all the powers of its parent territorial authority, or a community council, to which the parent authority may delegate powers. The purpose of these community bodies is to increase residents' participation in local government. The Local Government Act also introduced a new form of territorial local authority, the district council, established to serve areas of mixed rural and urban character.
The Local Government Commission was charged with the task of constituting the regional bodies, of which there were 22 (2 regional councils and 20 united councils) by 1983. As of 1996 there were also 93 county councils, 9 district councils, and 3 town districts. By 1999, a new administrative structure was instituted that divided local government into 17 regions that were subdivided into 57 districts and 16 cities. In 2003, there were 12 regional councils, 59 district councils and 15 city councils. Most units of local government are elected at three-year intervals. In boroughs the mayor is elected directly by the voters, while the council itself elects the chairman of a county council.