An image of the how electorates in the city of Sydney voted on same sex marriage.

In a country the size of Australia, sometimes political differences are sharpened by distance. On SSM, the great divides can be just across the street.

Australians turned out en masse to have their say on whether same-sex couples should be allowed to marry. (Yep, it turns out even teenage voters know what a postbox is.)

The survey result was a resounding yes, with 62 per cent of voters in favour of legalising SSM.

On this map, every electorate is shaded based on voters' response to the SSM survey: blue seats are less supportive and orange seats are more supportive.

As the map makes clear, there was majority support for same-sex marriage in every state and territory.

In fact, voters in every single electorate in Tasmania, South Australia, Western Australia, the NT and the ACT recorded a majority response for 'yes'.

But the situation was more complicated in the eastern states.



Victoria had the highest response rate and the highest overall support for SSM. This was on show in the capital, with the seat of Melbourne recording 84 per cent support, the highest in the nation.

But Melbourne also offers a glimpse of another trend: the biggest divisions between voters aren't seen across vast distances but right next door.

The contrast is on show in the seat of Wills and its neighbour to the north, Calwell.

The only thing dividing those two seats, for much of their shared boundary, is the Western Ring Road. But voters' views on SSM are vastly different when you cross that boundary.

In Wills, support was 70 per cent. But head north into Calwell and it falls to 43 per cent.

We can't know for sure what drives this abrupt change. But Census data does provide some hints.

Calwell is home to large Catholic and Muslim populations, and people with 'no religion' make up only 13 per cent of the population. But in Wills, 32 per cent of people identify as non-religious.

That's significant because the proportion of non-religious residents in an electorate has a closer statistical relationship to voters' views on SSM than any other demographic variable.

Keep in mind, of course: that's a correlation, not necessarily a causal relationship.

The trend seen in microcosm in Melbourne is writ large in Sydney, home of the Mardi Gras and birthplace of Australia's LGBTI rights movement.

Orange in the east and blue in the west tells the story here.

The inner-city seat of Sydney, along with Wentworth to its east and Grayndler to its west, are all in the top five most supportive seats in the country.

But cross Prospect Road from Grayndler into Watson and support for SSM plummets to 30 per cent.

One seat further west takes you to Blaxland; it's the electorate most opposed to same-sex marriage anywhere in the country.

In all, 12 of the 17 electorates that returned a majority 'no' to SSM are in western Sydney.

A general pattern of lower support in outer suburban areas was expected, but the shape of the result in Sydney's west did surprise many.

One thing's for certain: the pattern isn't formed along party lines.

Of the 10 seats with the strongest opposition to same-sex marriage, nine of them are held by the Labor Party, which had committed to support same-sex marriage before the last election.

And in Tony Abbott's seat of Warringah, support sits at 75 per cent, despite the former prime minister campaigning strongly against same-sex marriage.

So if it's not party politics, what's going on?

The difference in this survey is people were being asked to provide their opinion on just one issue, unlike an election where they're having to balance competing priorities alongside party preferences.

With a social issue on the table, voters can turn away from their usual motivations, which University of Sydney political scientist Shaun Ratcliff says are often driven by economics.

Instead, personal factors like religion, cultural background, income level and education level all come into play.

Dr Ratcliff says SSM stands apart from much of what drives typical voter behaviour in Australia.

"Attitudes to SSM are largely unrelated to other political and policy preferences for a very large proportion of the Australian electorate," he says.

As always, Queensland likes to do things differently. Up north, distance does show up as a distinct factor.

Like Sydney and Melbourne, Brisbane has inner-city seats among the top 10 seats most supportive of SSM.

But unlike its southern neighbours, Queensland's areas of least support were not the outer suburbs of its capital, but its regions — particularly the seats of Kennedy, Maranoa and Groom.

Out of the 17 electorates nationwide that voted 'no', these three were the only ones based in regional areas, and the 'yes' vote in these seats was higher than it was in many parts of western Sydney.

In regional Australia, support ranged from 71 per cent in Ballarat to 44 per cent in Maranoa.

In the north Queensland seat of Kennedy, long-serving MP Bob Katter once claimed none of his constituents were gay. And yet, 47 per cent of its voters backed SSM.

Once more, this issue doesn't necessarily divide Australia in the way you might think.

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