That means Aucklanders will have a more powerful voice in Government decisions, after next year's general election.
The census attempts to count everyone in NZ on census night and provides a snapshot of society.
Statistics NZ's population clock estimates the number of people usually resident here at 4,486,000, but that allows for people who were out of the country on census day or who did not fill in census forms. The census number is likely to be slightly lower.
By 2031, Statistics NZ estimates, the population will hit 5.2 million.
Auckland has clocked up the highest growth, with a third of the nation's population now calling the Super City home. One rural mayor claims Auckland's boom has come at a cost.
"For small and rural provincial towns it's the two 'As' - Auckland and Australia," said Opotiki Mayor John Forbes, who chairs a Local Government NZ group representing rural districts. He believes some towns will simply disappear or be amalgamated with neighbours.
Different worlds
Sally Selwood was born in the third quarter of 1952, as the population of New Zealand reached two million.
Now she's expecting her first grandchild as the population touches on 4.5 million. The two childhoods will be worlds apart.
Selwood's granddaughter will be born into a world where touch screen phones, laptops, Skype, flat screen TVs, internet banking, and Facebook are an everyday reality, but beyond the wildest imaginings of her grandmother growing up in Nelson in the 1950s.
"We had a freedom that kids these days simply don't have," she said. "We used a great deal of imaginative play - saving money to buy a pram from the op-shop to wreck it for the axle to make a trolley.
"These days a lot of kids spend time on computers and are more passive in their activities."
In Selwood's day, if you didn't get there by bike or by foot "you didn't go", you never got dropped off at school, and seat belts - "What were they?"
Buying a coffee "to go" was unheard-of; throwing away the cup unthinkable.
Selwood says her grandchild faces a complex world with pressures to grow up fast. "I want her to have a carefree childhood with the freedom to be a child, rather than a child with adult worries."