Originaly called the Corris, Machynlleth & River Dovey Tramroad, the Corris Railway is a narrow gauge (2' 3") railway dating back to the 1850's. The line was initially built as a horse-and-gravity-worked tramroad to carry slate from the quarries of Corris Uchaf and Aberllefenni to the nearest navigable port of Cei Ward near Derwenlas on the Afon Dyfi (River Dovey), where it was loaded into ships and carried to its many destinations. In 1864 with the arrival at Machynlleth of the Newtown and Machynlleth Railway (becoming part of the Cambrian Railway in the same year) the line ceased to deliver direct to shipping, and instead transhipped its slate to the standard gauge railway.
In 1878 the line was acquired by a London company, Imperial Tramways Ltd, and three steam locomotives and ten purpose-built passenger carriages were introduced, although due to a dispute with the quarry owners, passenger services were suspended until 1883. For the rest of the nineteenth century the Railway was very prosperous, developing a substantial tourist traffic. From 1892, Imperial Tramways was based in Bristol, sharing offices and management with the Bristol Tramways firm.
The 20th century brought with it a decline in the slate industry, followed by increasing competition from road transport. The railway ran its own successful bus services, using vehicles provided from Bristol, and it was probably more from a desire to control these services than to acquire the Corris Railway itself that led to the Great Western Railway purchasing the line from Imperial Tramways in 1930. Soon afterwards passenger services were withdrawn. The line continued in use for goods only until 1948, when it became one of the first to be closed by the newly-nationalised British Railways. The line was dismantled soon after closure, the surviving locomotives and rolling stock finding a new life on the nearby Talyllyn Railway Society, where they are still to be seen in operation.
In December 1966 a group of Talyllyn Railway Society members from the East Midlands formed what became Corris Railway Society. Visible signs of their activity came with the opening of the first stage of the Corris Railway Museum in 1970, using the remaining buildings of Corris station. A "demonstration track" was laid at the south end of the Station Yard, adjacent the Museum, in 1971, but bureaucratic obstacles prevented it initially reaching more than a few hundred yards.
In 1981, Maespoeth engine shed and yard about three-quarters of a mile from Corris was returned to the Railway from the Forestry Commission was returned to the Railway, and the Society has transformed it back into a well-equipped engine shed and workshop. Approval for reinstatement of track to connect Corris and Maespoeth was finally received in 1984, and in 1985 the Society celebrated by running the "First train back to Corris" after a break of thirty-seven years.