NZ functional urban area
The four-digit code identifying a New Zealand functional urban area in the statistical standard for geographic areas kept by Stats NZ.
A functional urban area is an urban core together with the surrounding area that commutes into it, so it describes a labor market rather than a built-up footprint. There are 53.
Four digits. The first states the type, which is set by the population of the core alone: 1 metropolitan area, 2 large regional centre, 3 medium regional centre, 4 small regional centre, 9 outside any functional urban area. The remaining three are numbered north to south. Auckland is 1001, Whangarei 2001, Cambridge 3001.
Because the leading digit is a population band, a reclassification changes the code. Stats NZ applies the bands with judgment rather than mechanically, and classified Greymouth as a medium regional centre despite a core under 10,000.
A functional urban area usually shares its name with the urban area at its core, so Stats NZ advises naming the type alongside it: Christchurch metropolitan area rather than Christchurch. The 2023 classification is interim and will be revised once census commuting data is available.