The National Union of Railwaymen of Australia was first registered under the Commonwealth's industrial relations legislation in March 1933. It was soon de-registered in July 1933 and many members of this original union were eventually covered by a second union of the same name, which registered on 7 December 1938. The NUR amalgamated with the Government Railways Transport Staff Association in 1938, with the Department of Main Roads Employees' Union in 1942 and the Government Tramway Electrical Branch Workers' Association around 1944-45. The Union continued under this name until 1982 when it changed to the National Union of Rail Workers of Australia. In 1993 the union amalgamated with the Australian Federated Union of Locomotive Enginemen, the Australian Tramway & Motor Omnibus Employees' Association and the Australian Railways Union to form the Australian Rail Tram & Bus Industry Union.

The Railway Service Association formed in 1930 from the amalgamation of the New South Wales Government Railways Permanent Way Association and the Association of Employees (Mechanical Branch) of the NSW Railways (unions registered since 1918). In 1933 the RSA as a State Industrial Union was renamed and registered in New South Wales as the National Union of Railwaymen, NSW Branch - a predecessor to the Commonwealth registered National Union of Railwaymen of Australia.

The association amalgamated with the National Union of Railwaymen of Australia around 1945.