END OF THE LINE FOR THE NITRATE RAILWAYS
The geographical and historical context
Nitrates, or, more precisely, sodium nitrates, are found in what is known locally as caliche, i.e. nitrate-bearing rock or ore, mainly in an intermittent band up to 45 km wide on the pampa, at altitudes of from 950 to 1 300 metres above sea level between the Pacific Ocean and the Andes mountain chain and at latitudes from 19°S to 26°S. The caliche was usually concentrated in situ into nitrate at factories, known locally as oficinas. Nitrates are used as an agricultural fertilizer, in the manufacture of explosives and in other industrial applications.
Before the War of the Pacific (1879 to 1883), the embryonic nitrate production was concentrated in Peru’s Tarapaca Province, with lesser amounts being contributed by the Chilean-owned Compania de Salitre y Ferrocarril de Antofagasta in Bolivia’s Departmento del Litoral (the raising of a tax on which, by being contrary to Article 4 of the 1874 Treaty between Chile and Bolivia, was the immediate cause of the War) and the first shipments from Chile’s Department of Taltal. As a result of the War, both Peru’s and Bolivia’s nitrate producing zones were ceded to Chile, which, henceforth, held a virtual worldwide monopoly in the production of natural nitrates.
The said narrow band is at an average of some 50 km from the coast (which is obviously at sea level) and in the driest region on the planet through which only one river passes, the El Loa, which has an average flow rate by the time it reaches the sea of just 0.24 m3/second.1 Hence, due both to steep slopes and extremely meagre flow it cannot be navigated even by raft.
The dependence of the nitrate industry on rail
Because of the aridity of the climate, roads in the nitrate zone do not necessarily have to be paved to be usable the whole year round. Towards the end of the nitrate industry’s boom years, from around 1890 to 1930, lorries had appeared on the scene but their carrying capacity rarely exceeded two or three tons. 1½ tons was the most that could be handled by a lorry based on Ford’s model A chassis, which held much of the market in the early 1930s.² Since by the late 1920s, the yearly production of nitrates for export had reached almost three million tons, road
