Yes the border is not straight, as would be assumed
The follow is a piece taken from this page
http://www.ga.gov.au/scientific-topics/geographic-information/dimensions/border-lengthsA glance at most maps of Australia will tell you something that isn't quite true. The border which runs along the eastern edge of Western Australia is not actually one continuous straight line.
The survey of the Western Australian border was first discussed in 1911, but it wasn't until 1922 that an agreement was signed between then Prime Minister W.M. Hughes, the Acting Premier for South Australia, Mr. Bice, and the Premier of Western Australia, Sir James Mitchell. The agreement set out the border as being a line determined by the 129th meridian east longitude. However, the agreement required that the boundary be defined by lines running north and south from independently fixed points at Deakin and Argyle. When survey work began on the South Australia - Northern Territory border in 1963, it was quickly realised that the earlier agreement precluded the possibility of these lines meeting exactly.
Precise survey methods confirmed this and in June 1968 two monuments approximately 127 metres apart were erected at the junction of the boundaries. This ceremony was attended by the respective Surveyors General, H.Comm from Western Australia, H.A. Bailey from South Australia, and P.J. Wells from the Northern Territory. The monuments common to all three jurisdictions was named Surveyor General's Corner at the suggestion of the Director of National Mapping. One interesting piece of trivia is that fewer people have visited this site than have been to the South Pole.
Cheers
John
