Castlereagh Highway is a state

highway A highway is any public or private road or other public way on land. It includes not just major roads, but also other public roads and rights of way. In the United States, it is also used as an equivalent term to controlled-access highway, or ...

located in

New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...

and

Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

, Australia. From north to south the highway traverses

South West Queensland South West Queensland is a remote region in the Australian state of Queensland which covers . The region lies to the south of Central West Queensland and west of the Darling Downs and includes the Maranoa, Queensland, Maranoa district and parts o ...

and the

North West Slopes The North West Slopes region of New South Wales, Australia, refers generally to the area west of the Northern Tablelands, to the north of the Central West region and to the east of the Far West region. Despite its name, the region is in north- ...

, Orana, and Central West

regions of New South Wales In the state of New South Wales, Australia, there are many areas which are commonly known by regional names. Regions are areas that share similar characteristics. These characteristics may be natural such as the Murray River, the coastline, or t ...

. The highway is part of the

Great Inland Way The Great Inland Way is an Australian road route from Sydney, New South Wales to Cairns in Queensland. It has been designated by the Queensland Government as a State Strategic Touring Route. The route The New South Wales section is from Sydney ...

linking

Sydney Sydney is the capital city of the States and territories of Australia, state of New South Wales and the List of cities in Australia by population, most populous city in Australia. Located on Australia's east coast, the metropolis surrounds Syd ...

and

Cairns Cairns (; ) is a city in the Cairns Region, Queensland, Australia, on the tropical north east coast of Far North Queensland. In the , Cairns had a population of 153,181 people. The city was founded in 1876 and named after William Cairns, Sir W ...

, and provides all-weather access to rugged black opal country of

Lightning Ridge Lightning Ridge is a small outback town in north-western New South Wales, Australia. Part of Walgett Shire, Lightning Ridge is situated near the southern border of Queensland, about east of the Castlereagh Highway. The Lightning Ridge area is ...

. Castlereagh Highway was named after the

Castlereagh River The Castlereagh River is located in the central–western district of New South Wales, Australia. It is part of the Macquarie-Castlereagh catchment within the Murray–Darling basin and is an unregulated river, meaning no dams or storage have b ...

, which it parallels for most of its journey north from

Gilgandra Gilgandra is a country town in the Orana region of New South Wales, Australia, and services the surrounding agricultural area where wheat is grown extensively together with other cereal crops, and sheep and beef cattle are raised. The town i ...

Route

Castlereagh Highway commences at an intersection with

Carnarvon Highway Carnarvon Highway is a state highway in Queensland and New South Wales, Australia, linking the township of Rolleston in Queensland's Central Highlands Region, via the town of St George, eventually to Moree in northern New South Wales. It is ...

, south of , Queensland, and heads in a south-westerly direction via

Dirranbandi Dirranbandi is a rural town and locality in the Shire of Balonne, Queensland, Australia. The locality is on the border of Queensland with New South Wales. In the , the locality of Dirranbandi had a population of 610 people. Geography Dirranb ...

to Hebel, where it crosses the state border with New South Wales just beyond and continues in a southerly direction, past

Walgett Walgett is a town in northern New South Wales, Australia, and the seat of Walgett Shire. It is near the junctions of the Barwon and Namoi Rivers and the Kamilaroi and Castlereagh Highways. In 2021, Walgett had a population of 1,377. In the ...

, where it crosses the Barwon and

Namoi River The Namoi River, a major perennial river that is part of the Barwon catchment of the Murray–Darling basin, is located in the Northern Tablelands and North West Slopes districts of New South Wales, Australia. The Namoi River rises on the west ...

s and meets the Gwydir and

Kamilaroi Highway Kamilaroi Highway is a state highway located in the north-western region of New South Wales, Australia, and links via and to . The highway is named after the Kamilaroi Indigenous Australian people who live in the area. Route The highway b ...

s. Continuing south through

Coonamble Coonamble is a town on the central-western plains of New South Wales, Australia. It lies on the Castlereagh Highway north-west of Gilgandra. At the 2016 census, Coonamble had a population of 2,750. It is the regional hub for wheat growing and ...

, the highway crosses the

and meets the Oxley and

Newell Highway Newell Highway is a National Highway (Australia), national highway in New South Wales (NSW), Australia. It provides the major road link between southeastern Queensland and Victoria (state), Victoria via central NSW and as such carries large amo ...

s in

. It continues in a south-easterly direction through

Dunedoo Dunedoo ( ) is a village of 1,021 inhabitants situated within the Warrumbungle Shire of central western New South Wales, Australia. Dunedoo is well known to Australian travellers due to its distinctive name (''Dunny'' is a colloquial Australian ...

, sharing a short

concurrency Concurrent means happening at the same time. Concurrency, concurrent, or concurrence may refer to: Law * Concurrence, in jurisprudence, the need to prove both ''actus reus'' and ''mens rea'' * Concurring opinion (also called a "concurrence"), a ...

with

Golden Highway Golden Highway (also known as Mitchells Line of Road at its eastern end) is a highway, located in the Hunter and Orana regions of New South Wales, Australia. It runs eastwards from Dubbo towards Newcastle on the coast, allowing road transpo ...

, continues through the regional centres of

Gulgong Gulgong is a 19th-century gold rush town in the Central Tablelands and the wider Central West (New South Wales), Central West regions of the Australian States and territories of Australia, state of New South Wales. The town is situated within th ...

and

Mudgee Mudgee () is a town in the Central West (New South Wales), Central West of New South Wales, Australia. It is in the broad fertile Cudgegong River valley north-west of Sydney and is the largest town in the Mid-Western Regional Council Local gov ...

, through

Ilford Ilford is a large List of areas of London, town in East London, England, northeast of Charing Cross. Part of the London Borough of Redbridge, Ilford is within the Ceremonial counties of England, ceremonial county of Greater London. It had a po ...

and the junctions of Bathurst-Ilford Road and

Bylong Valley Way Bylong Valley Way is a New South Wales regional road linking Golden Highway near Sandy Hollow, New South Wales, Sandy Hollow to Castlereagh Highway near Ilford, New South Wales, Ilford. It is named after the Bylong Valley, through which the road ...

, before eventually terminating at an interchange with

Great Western Highway Great Western Highway is a state highway in New South Wales, Australia. From east to west, the highway links Sydney with Bathurst, New South Wales, Bathurst, on the state's Central Tablelands. The highway also has local road names between the ...

at Marrangaroo, north-west of Lithgow.

History

The passing of the ''Main Roads Act of 1924'' through the

Parliament of New South Wales The Parliament of New South Wales, formally the Legislature of New South Wales, (definition of "The Legislature") is the bicameral legislative body of the Australian state of New South Wales (NSW). It consists of the Monarch, the New South Wa ...

provided for the declaration of Main Roads, roads partially funded by the State government through the

Main Roads Board The Main Roads Board was an agency of the Government of New South Wales, responsible for planning, constructing and maintaining road infrastructure in New South Wales, Australia. History The Main Roads Board (MRB) was founded on 1 January 1925 ...

(MRB, later

Transport for NSW Transport for NSW (TfNSW) is a Government of New South Wales, New South Wales Government transport services and roads List of New South Wales government agencies, agency established on 1 November 2011. The agency is a different entity to the NSW ...

). Main Road No. 55 was declared from the intersection with

near Marrangaroo, via Ilford, Mudgee, and Gulgong to Craboon (and continuing northwards via Coolah eventually to the intersection with

Oxley Highway Oxley Highway is a rural highway in New South Wales, Australia, linking Nevertire, Gilgandra, Coonabarabran, Tamworth, and Walcha to Port Macquarie, on the coast of the Tasman Sea. It was named to commemorate John Oxley, the first European t ...

Mullaley Mullaley is a village in the Gunnedah Shire, New South Wales, Australia. Geography Mullaley is on the Oxley Highway, 38 km west of Gunnedah. The Coxs Creek runs across the highway on the western side of the village. Mullaley is on the cr ...

), Main Road No. 56 was declared from Walgett, via Coonamble to Gilgandra (and continuing southwards via Dubbo, Forbes, Cowra, Yass and Canberra eventually to the intersection with Queanbeyan-Braidwood Road, today Kings Highway, at

Queanbeyan Queanbeyan ( ) is a city in south-eastern New South Wales, Australia, located adjacent to the Australian Capital Territory in the Southern Tablelands region. Located on the Queanbeyan River, the city is the council seat of the Queanbeyan-Pale ...

), and Main Road No. 205 was declared from Craboon via Dunedoo to Mendooran (and continuing northwards via Tooraweenah to Coonamble), on the same day, 8 August 1928. With the passing of the ''Main Roads (Amendment) Act of 1929'' to provide for additional declarations of State Highways and Trunk Roads, these were amended to Trunk Roads 55 and 56 and Main Road 205 on 8 April 1929. Trunk Road 77 was later declared from the intersection with Oxley Highway at Gilgandra via Mendooran and Dunedoo, to Trunk Road 55 at Craboon, on 16 March 1938. The Department of Main Roads, which had succeeded the MRB in 1932, declared State Highway 18 on 16 March 1938, from the intersection with State Highway 11 (later known as

) at Gilgandra via Coonamble and Walgett to the state border with Queensland near Brenda; with the declaration of State Highway 17 (later known as

) on the same day, the northern end of Trunk Road 56 was truncated to meet State Highway 17 at Forbes, as a result. State Highway 18 was named Castlereagh Highway on 12 May 1954, after the

, with the river named in honour of

Lord Castlereagh Robert Stewart, 2nd Marquess of Londonderry, (18 June 1769 – 12 August 1822), usually known as Lord Castlereagh, derived from the courtesy title Viscount Castlereagh ( ) by which he was styled from 1796 to 1821, was an Irish-born British st ...

. The alignment north of Lightning Ridge was altered on 17 June 1959 to meet the state border with Queensland at Hebel via Angledool, instead of via Brenda. In December 1982, a 15 kilometre deviation opened south of

as part of the

Windamere Dam Windamere Dam is a minor ungated rock fill with clay core embankment dam with an uncontrolled unlined rock cutting spillway across the Cudgegong River at Cudgegong, upstream of Mudgee in the Central Tablelands of New South Wales, Australia. T ...

project. The

Roads & Traffic Authority The Roads & Traffic Authority (RTA) was an Statutory authority, agency of the Government of New South Wales responsible for major road infrastructure, licensing of drivers, and registration of motor vehicles. The RTA directly managed state ...

, succeeding the New South Wales DMR in 1989, extended the highway declaration south from Gilgandra via Dunedoo and Mudgee to Marrangaroo on 3 October 1997, subsuming Main Road 77 (previously Trunk Road 77). The southern end of Main Road 56 (previously Trunk Road 56) was truncated to meet State Highway 18 east of Craboon, as a result. The passing of the ''Roads Act of 1993'' through the

updated road classifications and the way they could be declared within New South Wales. Under this act, Castlereagh Highway today retains its declaration as Highway 18, from the state border with Queensland at Hebel to the intersection with Oxley Highway in Gilgrandra, then from the intersection with Newell Highway in Gilgandra to the intersection with Golden Highway in Dunedoo, then from the intersection with Golden Highway near Craboon to the interchange with

at Marrangaroo. Within New South Wales, the highway was signed National Route 55 in 1974 from Gilgandra to Walgett, and State Route 86 south of Gilgandra; National Route 55 was extended north from Walgett to the border with Queensland in 1983. Queensland however signed Carnarvon Highway as National Route 55 between 1983 and 1997 rather than Castlereagh Highway, causing a major discrepancy for many years in that National Route 55 met the border at Hebel but abruptly begun again over east along the border at

Mungindi Mungindi is a town and locality on the border of New South Wales (NSW) and Queensland, Australia. The town is within Moree Plains Shire in New South Wales. Within Queensland, the locality is split between the Shire of Balonne (the western part) ...

. The Queensland Road Department changed this in 1997 and signed National Route 55 over the border north to St George, and eventually to

Charters Towers Charters Towers is a rural town in the Charters Towers Region, Queensland, Australia. It is by road south-west from Townsville on the Flinders Highway. During the last quarter of the 19th century, the town boomed as the rich gold deposits und ...

in later years. With both states' conversion to the newer alphanumeric system between 2005 and 2013, its route number was updated to route A7 between Rolleston and Roma and A55 between Roma and the state border for the highway within Queensland in 2005, and eventually along the remaining highway within New South Wales as route B55 in 2013.

Upgrades

The

Roads of Strategic Importance Roads of Strategic Importance (ROSI) is a $5.8 billion initiative of the Australian Government designed to help connect regional businesses to local and international markets, and to better connect regional communities. The source for this article ...

initiative, last updated in March 2022, includes the following project for Castlereagh Highway.

Carnarvon Highway intersection upgrade

A project to upgrade the intersection with

at a cost of $3.4 million was completed in mid-2022. This project was targeted for "early works" by the Queensland Government.

Major junctions

References