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I need a dataset of admin 1 boundaries for many countries, but particularly Australia and New Zealand. Using the current 3.6 boundaries from GADM, they seem to depart from the available Regional Council boundaries significantly, and I don't understand why.

enter image description here

In this map:

  • Yellow is the Regional Council 2017 "clipped, HD" boundaries from stats.govt.nz here
  • Cyan is the GADM Admin 1 boundaries, 3.6.
  • Green dots are the Territorial Authority boundaries 2017 (same dataset as REGC).

The GADM boundaries mostly line up with the REGC boundaries...but depart significantly in places. And in some places follow the TA boundaries instead.

What's the explanation for this?

1 Answer 1

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The explanation is, that the Kiwis changed some administrative borders while they left others as they were (districts got changed, counties stayed the same most likely) and GADM mixed them somehow up.

The more important and interesting question is, which data you should use. Basically I would always go with official data. If that data isn't up to date, it's still not your fault, once you name your source and the date of data-acquisition.

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  • Can you expand on "changed some administrative borders"? I compared the 2001 boundaries with 2018 and nothing much has changed. Jun 26, 2018 at 2:05
  • What is there to expand? At some time in the past district borders were drawn which didn't overlap with the county-border - or vice versa. I got no idea when the discrepancy occured. The change of administrative borders is quite common, only the discrepancy is not.
    – Erik
    Jun 26, 2018 at 8:13
  • Well, I'm asking for evidence that that's actually what's going on here, because according to my evidence, it's not. (I had wondered the same thing). Jun 26, 2018 at 23:43
  • Only thing I can do is guesswork =) I think you should ask someone responsible for geodata from the stats.gov.nz website, or better from the NZ-adminstration.
    – Erik
    Jun 27, 2018 at 6:29
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    Guesswork is good :) I just think in this particular case that particular guess was not correct :) Jun 27, 2018 at 8:10

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