The most significant man-made boundary in Australia is the border between Western Australia and South Australia. This border was established in 1897 and runs along the 129th meridian east. It is the longest straight line boundary in the world, stretching for over 1,600 kilometres. The border was created as a result of a dispute between Western Australia and South Australia over the ownership of land in the Great Australian Bight.
Other man-made boundaries in Australia include:
* The border between New South Wales and Queensland, which runs along the 141st meridian east. This border was established in 1859 and was based on the original boundary of the colony of New South Wales.
* The border between Victoria and South Australia, which runs along the 141st meridian east. This border was established in 1839 and was based on the original boundary of the colony of South Australia.
* The border between Tasmania and Victoria, which runs along the Bass Strait. This border was established in 1856 and was based on the original boundary of the colony of Tasmania.
* The border between the Northern Territory and South Australia, which runs along the 138th meridian east. This border was established in 1863 and was based on the original boundary of the colony of South Australia.
* The border between the Australian Capital Territory and New South Wales, which runs along the Murrumbidgee River. This border was established in 1911 and was based on the original boundary of the Australian Capital Territory.
These are just a few examples of the many man-made boundaries that exist in Australia. These boundaries have played an important role in shaping the history and development of the country.