This was the world's first hydro-electric powered railway and began running electric tramcars in 1883. Its route ran generally east to west near the north coast of County Antrim. Portrush was and is a popular seaside resort and the countryside to the east is prosperous farmland. The original intention of the tramway was to provide railway connections for this area, linking to the Belfast & Northern Counties Railway's branch to Portrush from Coleraine (this latter line is one of the very few routes to survive and forms part of Northern Ireland Railways).

Apart from passengers the promoters of the tramway also intended to carry freight and expected a healthy income from this. Although innovative electric traction was selected the tramway also operated steam locos. The electric supply was picked up by the tram locos from a conductor rail alongside the track and, at road crossings, from an overhead wire. On opening, the first section, from Portrush to Bushmills (home of the world's oldest whiskey distillery), quickly demonstrated that the tramway's primary income would come from passenger traffic, especially tourists and day trippers. Within days of opening the company made arrangements for the carriage of passengers on from Bushmills to the Giant's Causeway using local coaches and jarveys.

This development encouraged the company to build an extension on from Bushmills along the clifftops to the Giant's Causeway and, especially in the summer season, it quickly proved very popular. This extension was and is very scenic and most of the photos of the tramway are of this section. Today, a new tourist line has been opened following much of this route using locos and rolling stock previously operated at Shane's Castle.

With seasonal tourist traffic asits mainstay the tramway operated successfully and moderately profitably - although winter economies were always necessary - through to the mid-1930s when increasing competition from road transport began to seriously affect its income. This combined with the rising costs of repair and the replacement of ageing tramcars. Nevertheless, the tramway struggled on through the war and into the late 1940s before finally closing in 1949. Government support for this, perhaps the most scenic and tourist-orientated narrow-gauge line in Northern Ireland, having been denied the company's assets were disposed of and the concern wound up. However, the recent establishment of a new narrow-gauge tourist line on the old trackbed has clearly demonstrated the value of such a tourist attraction.

A useful introduction to the tramway is that by J H McGuigan, The Giant's Causeway Tramway, Oakwood Press, 1964.