The Glasgow and South Western Railway (G&SWR) was a railway company in Scotland. It served a triangular area of south-west Scotland between Glasgow, Stranraer and Carlisle. It was formed on 28 October 1850 by the merger of two earlier railways, the Glasgow, Paisley, Kilmarnock and Ayr Railway and the Glasgow, Dumfries and Carlisle Railway. Already established in Ayrshire, it consolidated its position there and extended southwards, eventually reaching Stranraer. Its main business was mineral traffic, especially coal, and passengers, but its more southerly territory was very thinly populated and local traffic, passenger and goods, was limited, while operationally parts of its network were difficult.

The Caledonian Railway (CR) was a major Scottish railway company. It was formed in the early 19th century with the objective of forming a link between English railways and Glasgow. It progressively extended its network and reached Edinburgh and Aberdeen, with a dense network of branch lines in the area surrounding Glasgow. It was absorbed into the London, Midland and Scottish Railway in 1923. Many of its principal routes are still used, and the original main line between Carlisle and Glasgow is in use as part of the West Coast Main Line railway.