Dundalk, Co Louth, on the main Dublin to Belfast line, was at one time a major railway centre in Ireland, due largely to the establishment of the Great Northern Railway's main works there in the late 1890s. Dundalk was also the junction for the extensive Irish North West lines, which were taken over by the GNR and ran west out to the Atlantic coast at Bundoran via Clones and Enniskillen. Heading in an easterly direction, the Dundalk & Greenore Railway, built a line from Dundalk to Greenore port and was largely funded by the London North Western Railway. The GNR took over the working of the Greenore line in 1933. The D&GR was the first to close in 1951, though a short section of the line remained intact to serve Barrack St goods yard until 1996. The junction for the INW line was just south of the station at Dundalk Central, and only a stub of this closed 1957 line remains, this being the disused freight depot. The GNR Dundalk Works were run down in the late 1960s following CIE taken over in 1958.

Dundalk Station boasts a long island platform, connecting covered footbridge and typical GNR yellow brick station buildings, complete with small museum, cafe, and the preserved Dundalk Central signal cabin. Dundalk North cabin was demolished when the railcar stabling sidings were built on the up side of the station in recent times. Simplification of the trackwork and signalling around Dundalk Station in 1996 resulted in the removal of the extensive sidings on the down side, now a car park.