Urban areas are statistically defied areas with no administrative or legal basis. Urban area populations are defined internationally as towns with 1000 people or more. The urban area classification is designed to identify concentrated urban or semi-urban settlements without the distortions of administrative boundaries. Urban areas are made up of complete meshblocks and area units.
Prior to 1992 only the main and secondary urban areas had unique 2 digit codes. In the 1992 pattern the structure of the urban areas was changed to 3 digits, with unique codes for Minor Urban Areas as well as Main and Secondary Urban Areas
There is a three part hierarchal sub-division of urban areas into:
Main Urban Areas
Secondary Urban Areas
Minor Urban Areas
Main urban areas are very large urban areas centred on a city or major urban centre. Main urban areas have a minimum population of 30, 000 and are identified by codes between 001 and 100 such as 020, Wellington. In the 2013 dataset, there are 25 main urban areas.
Secondary urban areas were established at the 1981 Census of Population and Dwellings. They have a population between 10,000 and 29,999 and are centred on the large regional centres. Codes for secondary urban areas range between 101 and 200 such as 110, Blenheim. In the 2013 Dataset, there are 15 secondary urban areas.
The remainder of the statistically defined urbanised population of New Zealand are in minor urban areas. Minor urban areas are urbanised settlements (outside main and secondary urban areas), centred around smaller towns with a population between 1,000 and 9,999. Codes for minor urban areas range between 201 and 500.
Rural centres are also defined in the urban area field. Rural centres were established during the 1989 Review of Geostatistical Boundaries. Rural centres have no administrative or legal status, but are statistical units deified by complete area units. They have a population between 300 and 999. These are not termed urban under than standard international definition but identifying these settlements enables users to distinguish between rural dwellers living in true rural areas and those living in rural settlements or townships. The code for rural centres is 501.
There is a major review of urban areas approximately every 20 years. Minor alterations can also occur as a result of requests from territorial authorities, general public, government organisations and statistics New Zealand output needs.
As at 1stJuly 2007, Digital Boundary data became freely available.
Non-alignment of meshblock and cadastral boundaries is one of a number of reasons for meshblock boundary adjustments. Other reasons include requests from local authorities, the Local Government Commission or Electoral Representation Commission, and to make Census of Population and Dwellings enumeration processes easier.
To derive the urban area boundaries clipped to the coastline, meshblock polygons were dissolved to exclude meshblocks with a land/water attribute of Inlet or Oceanic.
From the meshblock pattern, higher geographies, including the 2013 Urban Areas were dissolved using the dissolve tool in the Arc GIS suite to create multiple output datasets.