The “blood-red stones” that gave Arrigorriaga are a reference to the iron ore in the ground beneath much of Vizcaya. These rich iron deposits, which extended from Arrigorriaga to Cantabria, have been known since Roman times, but it was not until the mid-19th century that they began to be mined using explosives and modern methods. Huge quantities of ore were exported to Belgium, France and especially Great Britain.

It was at the turn of the 20th century that the economic success and wealth of the Basque Country were at their greatest. Profits from mining created a powerful steel industry, banks were founded, shipbuilding flourished, railways were built, cement plants and paper mills opened and the whole Basque economy was swept along on a wave of expansion and optimism.
Atraction
Attracted by this industrial boom and the prospect of finding work easily, thousands of people converged on the Basque Country from all over Spain. Soon labourers from traditional farmhouses could be found side by side with rich factory owners and newly arrived industrial workers in all the towns around Bilbao.
In the early 1930’s, the municipality of Arrigorriaga had a population of around 4,000. By that time its industrial structure was firmly established and it was already the second biggest town in the Nervión valley.
Industrialization in Arrigorriaga started at the end of the 19th century with mining as its driving force, joined soon afterwards by the Harino Panadera flour mill, the Barbier Brothers´ nail factory and the company which would exert the greatest influence over the area in the following decades: the Papelera Española paper mill.
The opening of the mill brought with it a huge increase in the population, due especially to the influx of skilled workers from affiliated companies based mainly in Guipuzcoa, Navarre, Albacete and Zaragoza. In 1932 the paper mill provided 590 jobs. The second biggest employer was Hilaturas Ibaizábal, founded in 1925, which had a workforce of 275. After nearly a century in Arrigorriaga, the paper mill finally closed down in the 1990´s. Nowadays, Arrigorriaga boasts a solid industrial structure based on four modern industrial estates that house over 200 firms.