National's most and least valuable electorates

Big party vote wins in 10 key electorates with significantly higher than average voter turnouts proved to be the backbone to the National Party's remarkable 44.4 per cent party vote total.

I've decided to kick off a series looking at the most and least valuable electorates for National, Labour, New Zealand First, the Greens, The Opportunities Party, and the Māori Party to see if they dispel, or confirm, some of the commonly held myths about our political parties, as well as looking at some of the strengths, weaknesses and opportunities they present to the parties. To do this I've looked at the top 10 and bottom 10 electorates for each of those parties in terms of how many votes they contributed to their party's overall party vote tally.

I'll work through the parties in order of party votes received this election, so we'll kick off with National. It's clear that the backbone to National's support confirms the commonly held perception that affluent and rural areas back National heavily. So no surprises there.

What I think is interesting though is how high the turnout is in those electorates too. The top two electorates for voter turnout - Rodney and Selwyn - delivered National 15.16 percentage points (pp) and 14.61pp more party votes than National would get on the night. Even in Waikati, the third highest turnout where National's share of the party vote was the lowest of their top 10 most valuable electorates, it was still 9.40pp higher than the end result.

Those top 10 electorates delivered for National 20.96% of their overall party vote tally this election, despite only representing 15.8% of overall party votes cast across the entire country. National's ability to not only win big in terms of party votes, but also in terms of turnout in these 10 seats. You'll see later this week that Labour has the opposite problem, in that its support is somewhat more evenly spread out around the country.

Unsurprisingly, the seven Māori electorates are the seven worst performing electorates for National, with Te Tai Tonga delivering National 12.47% of the party vote in that electorate being the only standout. But as National doesn't campaign in those electorates I've removed them from this analysis as it doesn't really tell us anything we didn't know before hand.

Where things get more interesting is when you start to look at National's least valuable electorates outside of the seven Māori electorates.

Manukau East, as I've written previously, was the sole electorate in the country to experience a swing to the right. While that, and the fact that National also grew their party vote in Manukau East too, will be welcome news for National, it's also National's second least valuable electorate in the country (excluding the Māori electorates as discussed above). Likewise other electorates where National did grow their share of the party vote in Auckland like Māngere, Manurewa, and Kelston, are all electorates with some of the lowest voter turnout rates. So again, National can be pleased it's won some extra votes in those seats, they're not in big enough quantities to make a meaningful difference.

What is interesting is that of the top 10 electorates for turnout, only Wellington Central makes an appearance in National's least valuable seats.

When you start to look at the broader picture, 39.7% of National's support comes from its top 20 seats, and 67% of it comes from half of all electorates, illustrating just how dependent National is on those electorates with large turnouts voting for National in large numbers. 

While this is clearly a strength of National's, it's also their key weakness. Should they lose even a few percentage points of support in those key seats, it has a much larger effect on National's overall prospects. If you were Labour looking ahead to the 2020 election, you'd be asking yourself the two questions of how to you maximise your own turnout in your safe seats, but also how can you steal back some gains from National in what are some pretty clearly defined geographical areas, the rural fringes of Auckland and the inner city suburbs of Epsom, Tāmaki, and the North Shore.

I think these a selection of electorates that, if National can maintain their strength in those top 10, could also soon join them, they are:

  1. Coromandel (6th for turnout, 50.98% party vote for National)
  2. Ōtaki (10th turnout, 46.03% party vote)
  3. Whangarei (11th turnout, 44.85% party vote)
  4. Northland (15th turnout, 46.18% party vote)
  5. Wairarapa (16th turnout, 48.64% party vote)
  6. Taupō (17th turnout, 53.74% party vote)
  7. Tauranga (19th turnout, 52.62% party vote)

What ties all these electorates together is that they all have much higher than average voter turnout rates, and they all party voted for National at a higher rate than the rest of the country. I think Whangarei and Northland could be very interesting in that regard, as with Shane Jones and Winston Peters respectively in those electorates, they boosted New Zealand First's party votes there too, meaning that if New Zealand First implodes this Parliament, then National stands to benefit greater.

Coromandel, Ōtaki, Wairarapa, and Taupō electorates are all what should be strong, provincial electorates for National, and Coromandel and Ōtaki in particular should lean that way further through a combination of rapidly aging populations and in Ōtaki's case especially, some massive infrastructure projects in the works over the coming five years.