The choice of route was contentious, with proposals favouring gentler gradients or closer connections to population centres. Securing finance for so ambitious a line proved difficult, prompting engineer Joseph Locke to revise the plans by abandoning a summit tunnel in favour of steeper gradients, reducing cost and construction time.
Sparse local population limited the development of branch lines, though some east–west routes later connected independently. At Carlisle, the creation of a joint station with other companies was fraught with difficulty, and the Lancaster and Carlisle Railway bore most of the expense amid resistance from its rivals.
Electrified in 1974, the route now forms a vital section of the West Coast Main Line (WCML). Also included are the Glasgow, Dumfries & Carlisle Railway, the Dumfries, Lochmaben & Lockerbie Railway and a small section of North British Railways track between Gretna & Longtown.
Three cycle route suggestions have also been included to offer a ride near to those routes.