In Dunedin North, the number of student residents contributes to the lowest median personal income of just $19,000, said 2013 Census general manager Gareth Meech.
The average house price in Epsom is $1.3 million, 10 times the average house price in Kaitaia of $138,800. And spending habits were very different too.
Brian Archibald, of Archibald Motors in Kaitaia, said Northlanders have adjusted to life on a low income.
"A lot of our vehicles we sell are in the $8000 to $12,000 bracket where people can afford to pay it back at $75 a week to $125 a week. And we sell a lot on no deposit."
Murray Selby, of Honda Cars in Newmarket, said the average price of new cars they sold was around $35,000, while most used cars were $20,000 to $25,000.
Political commentator Bryce Edwards said the figures, which had not been released by Statistics in this manner before, would be "incredibly useful" for understanding voter behaviour.
Dr Edwards said the figures showed "undoubtedly a correlation" between higher income electorates voting for more conservative parties, with lower incomes being more left-leaning.
"If you come across a poor person on the street, it's a good bet they are going to be a Labour voter, and if you come across a businessman on the street, he's a National voter."
However, those traditional voter patterns were changing, Dr Edwards said, as both main parties become more centric on the political spectrum.
The figures also show a breakdown in the ethnicities of electorates. Epsom's population of 61,878 comprises 62 per cent Europeans, 4 per cent Maori and 28 per cent Asian. In Northland, its 83,568 population is made up of 65 per cent European, 33 per cent Maori, and 2 per cent Asian.
Mike Sabin, National MP for Northland, said his electorate's rural community and socio-economic demography put it "worlds apart from Epsom".
However the focus on business growth was helping to lift incomes.
Wellington Central was the most highly educated electorate.
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