Default maximum speed limit in all states and territories of Australia (except the Northern Territory) is 100 or 110 kilometres per hour. In the Eastern States the default limit is 100, although some roads operate at a 110 km/h limit, while in Western Australia the default limit is 110. The Northern Territory has no default open-road limit. In most parts of this barren land the open road speed limit is difficult to enforce. These limits were set in the early 1970s at around the same time Australians switched to the metric system. Moves have been made over the years to change this limit (usually upwards in the more sparsely-populated states or downwards in the others), however, none have had much effect. | 
