The Apatamonasterio to Arrazola mining railway has what must be one of the most impressive sounding names of all our Spanish railways. Founded on the eve of the 20th century, it was in 1903 when the rails of the Compañía del Ferrocarril de Bilbao a Durango were prolonged from its terminal at Durango to a first branch line which took it to Apatamonasterio. This branch line was created for the main purpose of transporting iron ore from the mines at Arrazola to the mighty steelworks of Bilbao.

The tracks reached the mines just five months later, in February 1904, and a year later, also starting out from Apatamonasterio, they reached the town of Elorrio, completing a trident of lines at the heart of the Duranguesado rural district. The railway, originally steam powered, was later electrified, but the stretch from Elorrio quickly became more important than the modest mining spur. The mines reached crisis point in the mid-thirties, which sounded the death knell for this railway as it lost more and more traffic.

The last regular goods train ran along these rails towards the end of 1935, and the last passenger train scarcely a year later. The rails were not torn up but were used occasionally, either for carrying mineral ore during sporadic reopening of the mines, or for carrying lumber from any of the forests that lined the line. Like so many other industrial railways, its history eventually petered out and its total demise was finally announced in 1959, while the branch line to Elorrio was closed in the not so distant year of 1975.