The Swansea and Mumbles Railway was the venue for the world's first passenger horsecar railway service, located in Swansea, Wales, United Kingdom.

Originally built under an Act of Parliament of 1804 to move limestone from the quarries of Mumbles to Swansea and to the markets beyond, it carried the world's first fare-paying railway passengers under an agreement effective from 25 March 1807. It later moved from horse power to steam locomotion, and was finally converted to electric power, using the largest tram cars ever built for service in Britain, before closing in January 1960, in favour of motor buses.At the time of the railway's closure, it was claimed to have been the world's longest serving railway, although this distinction has to be qualified because other railways which were used solely for goods traffic (e.g. the Middleton Railway in Leeds, Yorkshire, dating from 1758) had been operating for longer.