The longest fence in the world is the "Dingo Fence" which runs down through South Australia, New South Wales and the Northern Territory, separating the cattle country from the sheep area. Estimates claim the fence is anywhere from 2000 to 9600kms, but the common estimate places the length around 5000kms (approx 3106mi). This means it is more than twice as long the Great Wall of China.

The fence is nearly 2 metres (6.5 feet) high and extends about 30 cm (11.8 inches) underground to keep the dingos from digging under it. There is a gate approximately every 19 kms (12 mi).

The fence is in place to protect the sheep industry from the ravages of dingoes and wild dogs. The Dingo Barrier Fence Scheme was first proposed in 1948 after a report by the then coordinating board (equivalent of the Rural Lands Protection Board), which recommended that a dingo barrier be established around the main/ potential sheep areas of the state. This was important at that stage as such a move united farmers with their "city cousins", the government.

The Dingo Barrier Fence is today funded from contributions from the government of approximately 60 per cent and from industry (via Local Government contributions) of approximately 40 per cent.