It was the beginning of a new era in cross border travel – which is now more commonly known as the Enterprise service.
Over the decades it’s been the subject of bomb threats during the Troubles, leading to the establishment of the Peace Train Organisation and the "Contraceptive Train" event organised by the Irish Women's Liberation Movement in May 1971.
During its first year in service there was one train which travelled in each direction. Today, there are eight daily departures and Translink says demand is on course to reach “an all-time high”.
Photographic exhibits are due to be launched in Lanyon Place Station in Belfast and Connolly Station on Thursday.
Translink Group chief executive Chris Conway: "Whatever your reason for travel, Enterprise has been there to connect us to family, friends and opportunity, evolving with the times and better connecting Belfast and Dublin."
Meanwhile Iarnrod Eireann chief executive Jim Meade said that the service has "a rich and evocative history".
He added: "The Enterprise train is a key economic and social connector for the people of
Dublin, Belfast and the stations in between and we look forward to another 75 years of its successful operation."
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