The Cambrian Line (Llinell y Cambrian), sometimes split into the Cambrian Main Line (Prif Linell y Cambrian) and Cambrian Coast Line (Llinell Arfordir y Cambrian) for its branches, is a railway line that runs from Shrewsbury, England, westwards to Aberystwyth and Pwllheli in Wales. Passenger train services are operated by Transport for Wales Rail between the western terminals of Pwllheli, in Gwynedd, and Aberystwyth, in Ceredigion, and the eastern terminal at Shrewsbury, Shropshire, as part of the Wales & Borders franchise. The railway line is widely regarded as scenic, as it passes through the Cambrian Mountains in central Wales, and along the coast of Cardigan Bay in Snowdonia National Park.
The line includes long sections of rural single track and is designated as a community rail partnership.
From Shrewsbury, the line heads west through northern Powys, serving the towns of Welshpool and Newtown, then continues further west calling at Caersws and then Machynlleth until reaching . At Dovey Junction, a short distance west of Machynlleth, the line splits into two branches: the southern branch goes to Aberystwyth, and the longer, northern branch continues to Pwllheli as the Cambrian Coast Line, crossing the River Mawddach by Barmouth Bridge. The section of the Cambrian Line between Shrewsbury and Aberystwyth may be called the Cambrian Main Line.
The line is made up of:
Shrewsbury and Welshpool Railway between Shrewsbury and Buttington
Oswestry and Newtown Railway between Buttington Junction and Newtown
Llanidloes and Newtown Railway between Newtown and Moat Lane Junction
Newtown and Machynlleth Railway between Moat Lane Junction and Machynlleth
Aberystwith and Welsh Coast Railway between Machynlleth and Aberystwyth/Pwllheli
These lines were constructed between 1855 and 1869. The section west of Buttington Junction became part of the Cambrian Railways in 1864.
The Cambrian Railways became part of the Great Western Railway under the Grouping Act of 1921.