The section from Trondheim to Hell opened on 22 July 1882. The next section, initially the Hell–Sunnan Line, opened in stages between 1902 and 1905. The line was lengthened to Snåsa Station on 30 October 1926 and then to Grong on 30 November 1929. Construction continued in a slow pace northwards, but was accelerated by the Wehrmacht after the 1940 occupation. The line was built through most of Helgeland and opened in seven stages to Dunderland Station in the next five years. The line then had to be brought up to standards before continuing northwards. It opened to Røkland Station in 1955, to Fauske Station in 1958 and to Bodø Station on 1 February 1962.