The Carmarthenshire Railway or Tramroad was a horse-worked plateway built in South Wales in 1803.
The Carmarthenshire Railway or Tramroad was authorised under an act of Parliament, the (42 Geo. 3. c. lxxx), of 3 June 1802 – the first granted for a public railway in Wales – to acquire the existing Carmarthenshire Dock at Llanelly and its feeder tramroad built by Alexander Raby by 1799, thus incidentally becoming the world's first dock-owning public railway company. The first from Cwmddyche ironworks down to the sea was open in May 1803 – the first stretch of public railway in use in Britain – and construction ceased in 1805 when the line had reached Gorslas. The engineer was named James Barnes and the gauge was approximately .
The line ceased to operate in or before 1844 and portions of its course were utilised by the Llanelly and Mynydd Mawr Railway, opened in 1881.