This dataset is the definitive set of statistical area 1 (SA1) boundaries as at 1 January 2018 as defined by Stats NZ.This version contains 29,889 SA1s.SA1 is a new output geography that allows the release of more detailed information about population characteristics than is available at the meshblock level. Built by joining meshblocks, SA1s have an ideal size range of 100–200 residents, and a maximum population of about 500. This is to minimise suppression of population data in multivariate statistics tables.The SA1 should: form a contiguous cluster of one or more meshblocks be either urban, rural, or water in character be small enough to: allow flexibility for aggregation to other statistical geographies allow users to aggregate areas into their own defined communities of interest form a nested hierarchy with statistical output geographies and administrative boundaries. It must: be built from meshblocks either define or aggregate to define SA2s, urban rural areas, territorial authorities, and regional councils.SA1s generally have a population of 100–200 residents, with some exceptions:SA1s with nil or nominal resident populations are created to represent remote mainland areas, unpopulated islands, inland water, inlets, or oceanic areas.Some SA1s in remote rural areas and urban industrial or business areas have fewer than 100 residents.Some SA1s that contain apartment blocks, retirement villages, and large non-residential facilities have more than 500 residents.The SA1 classification is a flat classification and in 2018 contains 29,889 SA1s – 29,873 digitised and 16 non-digitised. SA1s are not named. SA1 codes have seven digits starting with a ‘7’ and numbered approximately north to south. As new SA1s are created, they are given the next available numeric code.Digital boundary data became freely available on 1 July 2007.