Castlereagh Highway

Castlereagh Highway Queensland –New South Wales
Dick O'Brien Bridge (1991) carrying Castlereagh Highway over Barwon River, Walgett, NSW.
General information
Type	Highway
Length	790 km (491 mi)[1]
Gazetted	August 1928 (NSW, as Main Road 56)[2] March 1938 (NSW, as State Highway 18)[3]
Route number(s)	A55 (2005–present) (St George–QLD/NSW border) B55 (2013–present) (QLD/NSW border–Marrangaroo)
Former route number	National Route 55 (1997–2005) (St George–QLD/NSW border) National Route 55 (1974–2013) (QLD/NSW border–Gilgandra) State Route 86 (1974–2013) (Gilgandra–Marrangaroo)
Major junctions
North end	Carnarvon Highway St George, Queensland
	Gwydir Highway Kamilaroi Highway Newell Highway Oxley Highway Golden Highway
South end	Great Western Highway Marrangaroo, New South Wales
Location(s)
Major settlements	Dirranbandi, Hebel, Walgett, Coonamble, Gilgandra, Dunedoo, Mudgee
Highway system
Highways in Australia National Highway • Freeways in Australia Highways in Queensland Highways in New South Wales
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Castlereagh Highway is a 790-kilometre (490 mi)^[1] state highway located in New South Wales and Queensland, Australia. From north to south the highway traverses South West Queensland and the North West Slopes, Orana, and Central West regions of New South Wales.

The highway is part of the Great Inland Way linking Sydney and Cairns, and provides all-weather access to rugged black opal country of Lightning Ridge.^[4]

Castlereagh Highway was named after the Castlereagh River, which it parallels for most of its journey north from Gilgandra.