Hard to judge really. You could use a few different criteria to answer this question such as population and vegan business numbers, however, given there is no real way to tell - at best it would be a guess - and would not take into account smaller cities which may hold vegan enclaves.
On population alone Sydney currently is home to about 4.5 million people. Melbourne has just a little less at 4 million, and both have a similar amount of vegan businesses. I think it would be a safe bet to say both these capital cities would outdo the rest of the capitals - leaving Adelaide, Perth, Hobart, Canberra, Darwin and my current home city of Brisbane far far behind.
However, per capita, don't forget smaller towns such as Daylesford in Victoria, and Byron Bay in New South Wales - both are enclaves for alternative lifestyles and I would guess their vegan numbers would be quite high per capita, given their small populations.
But I digress, back to total numbers - and the title at this rate, based on number of population alone I would have to give to Sydney - although I wouldn't be suprise if it went down to the wire.
The city in Minnesota with the highest population is Minneapolis with a population of 392,880 in 2012.
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Bridgeport is the city with the highest population in Connecticut at 136,695 people.
With a population of around 4,285,000, Sydney is the largest city. It is the capital of the state of New South Wales, but not the capital of Australia.
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Australia's largest city by population is Sydney. In 2013, the population is close to 5 million.
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Sydney
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Cabramurra, 1488m
sydney