The Sodor and Mainland Railway was a standard gauge railway opened in 1853. It ran from the harbour at Kirk Ronan to Ballahoo via Rolf's Castle and Crovan's Gate, but it never actually reached the mainland due to a series of misfortunes. A plan to make a tunnel to the mainland failed when excavations through the Ballahoo Ridge collapsed, and a scheme to build a bridge across the Walney Channel was stopped by the Admiralty (ironically, they later became the driving force behind the unification of the North Western Railway and completion of the link to the mainland).
Many of the S&M staff originally came from Ireland or Scotland. It provided passenger services, but was primarily intended to be a goods line. Although plans were put in action to start a steamer ferry service from Kirk Ronan to Dublin, nothing much came of it.
The Sodor and Mainland Railway's finances collapsed in 1910 and finally the company joined with several other small railways on Sodor in 1914 to form the North Western Railway. However, only a small stretch of the S&M became part of the North Western's main line: namely the section between Kellsthorpe Road and a point just east of Crovan's Gate. Ballahoo was bypassed by the main line, but the old line is still in use as a secondary route connecting the town with the rest of Sodor and the mainland, along with the later Norramby branch. Further north the main line rejoins the branch and the S&M's proposed route to Vicarstown, which includes the unfinished tunnel under the Ballahoo Ridge.
The S&M did, at one time plan to build a western extension into Sodor's mountain country to connect to the expanding industrial town of Peel Godred. This plan, like the others, came to nothing and Peel Godred was serviced by the Mid Sodor Railway from 1880 until 1937, and a NWR branch (now run by electric engines).