The fence begins at Jimbour on the Darling Downs near Dalby and ends west of the Eyre Peninsula, on the Nullarbor cliffs near Nundroo. Most of it stands about 180 centimetres of wire mesh, unremarkable up close, staggering in aggregate. It was once even longer. Until 1980 the barrier ran more than 8,600 kilometres before sections were retired, leaving today's 5,614. It is not one fence but a chain of them, knitted together: the Wild Dog Barrier Fence across Queensland, the border fences down the New South Wales boundary, and the long Dog Fence through South Australia. The whole thing passes through Cameron Corner, the point where three states meet, where the Queensland and South Australian fences join. Parts are even lit at night by red and white lamps, powered by sunlight banked in batteries during the day.

A barrier this long does not maintain itself. In Queensland the Wild Dog Barrier Fence is worked by crews including two-person teams who patrol 300-kilometre sections twice a week, running out from depots at Quilpie and Roma. On the New South Wales side, a team of around thirteen staff each take responsibility for stretches of sixty to a hundred kilometres, walking and checking their portions every Monday and Friday in some of the most punishing country on the continent. It is endless, repetitive, solitary labour: find the break, mend the wire, drive on. A single hole can undo months of work. Holes discovered in the 1990s let dingo pups through, a reminder that against a clever predator and a vast distance, the fence is only ever as strong as its weakest metre.

The fence has reduced sheep losses, but the cost has been written into the land itself. Ecologist Mike Letnic has documented what happens where the dingo, Australia's top predator, is removed: biodiversity falls, and native mammals grow scarcer. Without dingoes to check them, kangaroos, emus and rabbits multiply and strip the pasture the fence was meant to protect. Stand on either side of the line in places and the difference is visible in the vegetation. The dingo's own status remains contested, native or introduced, pest or keystone, and the science increasingly suggests that the predator the fence excludes was holding the whole system in balance. By keeping dingoes out, the fence may have unleashed problems larger than the one it was built to solve.

The fence's history is not only ecological. When construction began in the 1880s, exclusion barriers like this one served the pastoral expansion that dispossessed Aboriginal people of their Country, and researchers such as Dr Justine Philip have argued that the fences also functioned to keep First Nations people off the land, a violent legacy rarely acknowledged in those terms. That past sits uneasily beside the fence's present. In late 2023, work began on a 32-kilometre extension to close the last gap between the New South Wales and South Australian fences, finished in 2024, even as ecologists called the project a step backwards. Officials defend the line as one tool among many against biosecurity threats. After more than a century, Australia is still asking whether the longest fence on Earth protects the country or scars it.