Auckland as an internal migration donor to the rest of New Zealand is nothing new

Newsroom reported a couple of weeks ago:

A growing number of people are turning their back on Auckland for greener and cheaper pastures of the regions.

A study by independent economist Benje Patterson indicates 33,000 left the super city in the four years to 2017, when its overall population grew by nearly 200,000 to nearly 1.7 million.

Patterson's study is available here. He makes use of a cool new dataset from Statistics New Zealand on internal migration, based on linked administrative data from the Integrated Data Infrastructure (IDI). However, even though the data he uses are new, the story is not. Auckland has long been an internal migration donor to the rest of New Zealand. This is a point that Jacques Poot and I have made at numerous conferences and seminars over the years.

In each Census (until the 2018 Census), people were asked where they were living five years previously (including in the 2013 Census, even though it was seven years after the 2006 Census). We can use that data to construct a matrix of flows from each region or territorial authority (TA) to every other region or TA. This essentially captures the number of people who changed the region or TA they lived in over a five-year period. It is different from the annual change data that Patterson uses, and in comparison the annual flows should be larger (because a person who migrates from Auckland to somewhere else, and then back to Auckland, within the five-year period, would not count as a migrant in these data).

Now, even though (in the Newsroom article) Patterson describes the five-yearly Census as "clunky", it is this Census data that shows Auckland's net out-migration to the rest of New Zealand is not a new phenomenon, and has been ongoing since the mid-1990s. Here's the data for the last four Censuses we have data for (not the 2018 Census, as we are still waiting) [*]:

The blue bars are the number of in-migrants to Auckland (from elsewhere in New Zealand) over each five-year period based on the Census data. The orange bars are the number of out-migrants from Auckland (to other places in New Zealand) over the same period. The smaller grey bar is the net internal migration to or from Auckland. Notice that for the last three periods (1996-2001, 2001-2006, and 2008-2013), net migration is negative. That means more out-migrants from Auckland to the rest of New Zealand than in-migrants from the rest of New Zealand to Auckland.

In other words, the new Statistics New Zealand data are not showing a trend that is new at all. It's something that has been going on for a long time. Which also puts the shallowness of the analysis in Patterson's report into context, such as this:

Auckland’s regional migration losses to the rest of New Zealand are not surprising when one considers the deterioration to housing affordability in Auckland that occurred over the period. Data from interest.co.nz shows that in April 2017, the median Auckland house was estimated to cost about 9.5 times the median household income. By comparison this ratio was 6.2 nationally.

The largest net out-migration from Auckland was in the 2001-2006 period (-18,000; or 3600 per year). Was Auckland housing affordability declining the fastest during that period? The truth is, the data don't provide an answer as to why on net people are moving away from Auckland.

Even the locations where they are moving to are not new. Newsroom notes that:

The regions closest to Auckland attracted two thirds of the exodus, with Tauranga proving to be the most popular, attracting an average 1144 people a year.

Waikato District on the southern fringe of Auckland gained an average of 3381 Aucklanders over the period, while Hamilton gained just over 1500 residents from Auckland.

The data indicates nearly 6000 Aucklanders moved to Northland over the four years, with gains spread evenly across Whangarei District, Far North and Kaipara.

Looking at the Census data for 2001 (so, the 1996-2001 period), the regions that Auckland lost (on net) the largest number of migrants to were (in order, and to the nearest 10 people) Bay of Plenty (-2800), Waikato (-2340), and Northland (-1600).

So, really there is nothing new here, other than the (albeit very useful, and more timely than the Census) dataset.

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[*] I'm using inter-regional migration flows here, rather than inter-TA flows. However, the story is very similar if I use inter-TA flows, because the Auckland region is the Auckland TA.