Drivers of NZ population changes

Stats NZ recently released new subnational population estimates for 2022. Not surprisingly this showed very low national population growth over the past year due to a net outflow of 11,500 international migrants, which partly offset the natural population growth (births minus deaths) of 24,100 people. The results for Auckland were also interesting, showing a net loss of 8,900 people over the year, with net internal migration being the biggest driver of this – over the year Auckland suffered an estimated net loss of 15,000 people to other areas of New Zealand. International migration contributed a further a net loss of 5,900 people, while natural growth was an increase of 12,000 people.

The chart below shows the relative contributions of net internal and international migration and natural population growth on annual population changes in each region over the past four years. To calculate these percentages, I divided the components of population change for each region by the total absolute value of those components. For example, using the numbers above for Auckland in 2022, the denominator is 15,000 + 5,900 + 12,000 = 32,900, and the proportion of this total change accounted for by internal migration is -15,000 / 32,900 = -46%. This shows the direction and the relative importance of each of the three sources of population change for each region.

As well as Auckland, negative net internal migration was a significant factor in population changes in the Nelson, West Coast, and Southland regions. International migration has obviously been very limited over the past two years but this seems likely to change in the near future.

Here’s a more detailed look across Territorial Authority areas. It’s interesting how many of the big cities have seen negative net internal migration over the past couple of years – as well as Auckland this has happened in Wellington, Lower Hutt, Palmerston North, Nelson city, Christchurch, Dunedin, and Invercargill. Could it be that rising cost of living is pushing NZers to move to cheaper locations? A full to/from analysis of internal migration flows would be very interesting, but it’s not possible with publicly available data as far as I know.

Finally here’s the Auckland local board areas. The internal migration impacts are quite different within Auckland (NB in this case, internal migration would include moving to another local board area within Auckland). Some local board areas gained population via internal migration in 2022, including Franklin, Papakura, Rodney, and Upper Harbour. Other areas saw proportionally large internal migration losses, including Albert-Eden, Devonport-Takapuna, Kaipātiki, Ōrākei, Waitematā, and Whau. It could be interesting to compare these with changes in housing supply and prices.

R code and data for these charts is here.