Premier Mike Baird this week revealed the new home for the museum would be on the banks of the Parramatta River, saying "it's about time western Sydney had one of the great cultural institutions right here in its heart." The data shows that distance strongly influences NSW visitor rates to the Powerhouse Museum, with those living within a 15 kilometre radius of the museum more likely to go to it. More than half of the museum's 160,000 NSW visitors whose postcodes were recorded came from four Sydney regions: inner west, city and east, and the lower and upper north. Visitor rates drop sharply towards the city's west and south-west, compared with a more gradual decline towards the north and south. Professor Paul James, director of Western Sydney University's Institute for Society and Culture, said the data showed that proximity was the key driver of visits and he expected the highest visitor rates to shift from the city to suburbs near Parramatta when the museum moved.

While the Premier says relocating the museum would allow it to "attract even more visitors", Professor James said he had seen no evidence for that claim and the higher density of inner Sydney means an Ultimo-based museum has a greater population within a closer distance to attract. Transport for NSW data shows that people are willing to travel, on average, about 20 minutes to attend leisure activities. "Leaving the museum in a historical building which was rebuilt for that purpose, leaving it where it is because its a hassle to move it, leaving it where it is because the numbers suggest that it's drawing a catchment from the area geographically connected to it all makes sense," Professor James said. "The only argument against that is the historical rebalancing of a massive emphasis on building infrastructure in the inner city... For me that's strong enough."

A business case for the museum's relocation has not been released but the state government believes annual visitors to the museum will reach about one million, or about double the current figure, by 2030. More than 170 prominent Sydney figures, including acress Cate Blanchett and former Premier Bob Carr, have signed a letter opposing the move. In response to the new data, Sydney lord mayor Clover Moore said western Sydney deserved cultural investment but but it should not come at the expense of the community "living in the heart" of the city. But supporters, including Parramatta Lord Mayor Paul Garrard and Sydney Business Chamber's David Borger, said the figures showed the museum was clearly an inner city institution and moving it to the "geographical centre" of Sydney would attract visitors from a wider spread of suburbs. Population projections show the fastest growth rates over the next 10 years will be in local government areas of Camden, Auburn, Liverpool and Blacktown and for the foreseeable future two in every three new Sydneysiders will be from western Sydney.

Deputy Premier and Minister for the Arts Troy Grant with NSW Premier Mike Baird. Credit:Louise Kennerley Urban planning expert Professor Peter Phibbs, from the University of Sydney, said planning strategies to develop Parramatta as an "alternative CBD" were vital but the debate over the museum's location, which pitted the city against the west, was "silly". "You can imagine in a city this big, a lot of places would simply run two museums. There's your city-centre one which might focus more on tourists and big bang stuff and then another branch in Parramatta," Professor Phibbs said. "The collection is certainly big enough." The existing museum will remain open until 2022 and Premier Baird has not said what the Ultimo site will be used for other than that he expects it to be "multi-use". The museum visitor postcode figures, which account for about half of all NSW visitors, were obtained under Freedom of Information laws and exclude international visitors and visitors to paid exhibitions, events, programs and school groups.

Fairfax Media's analysis used postcode population figures from the 2011 Census to calculate visitor rates per 1000 residents.