Castlereagh Highway
National Route 55
State Route 86
The Castlereagh Highway is a state highway in New South Wales, Australia. It also extends into Queensland. It has been given the route number 55. The highway was recently extended past Gilgandra to include state route 86. As such the Castlereagh Highway starts just outside of Lithgow at a junction with the Great Western Highway and runs in a north-westerly direction past Mudgee and Gulgong, past Gilgandra until it reaches the Queensland border at Hebel. From there it continues to the town of St George where it terminates. National route 55 continues from here as the Carnarvon Highway.