Southern railway line, Queensland

Southern railway line at The Summit in June 2015
Track gauge	3 ft 6 in (1,067 mm)

The Southern railway line serves the Darling Downs region of Queensland, Australia. The 197 kilometre long line branches from the Western line at Toowoomba, 161 kilometres west of Brisbane, and proceeds south through Warwick and Stanthorpe to the New South Wales/Queensland state border at Wallangarra.

The first section of the Southern railway opened from the end of the Main Line railway at Toowoomba to Millhill, a northern suburb of Warwick, on 9 January 1871, the line terminating there to save the cost of a bridge over the Condamine River.

In 1872, tin was discovered at Stanthorpe, but disagreement over the route to be taken through Warwick resulted in the approval to extend the line not being given until 1877. The difficult terrain south of Warwick required two tunnels, one through solid rock which took two years to excavate, and the line opened to Stanthorpe on 3 May 1881. The Dalveen Tunnel was added to the Queensland Heritage Register on 28 July 2000.

The Southern line was completed to Wallangarra on 14 February 1887. The first passenger trains between Brisbane and Sydney ran on 16 January 1888, when the New South Wales Main Northern line opened. Trains operated via Gowrie Junction on the Western line until 1915 when the Drayton Deviation opened, shaving 30 minutes off journey times.