Copper mining has long been the most consistent of Chilean exports; and in current day, it still accounts for almost one-third of all foreign trade. Yet that 1/3 is down from a peak of almost 75% in earlier years.
Copper has been mined in the land area between central Chile and southern Peru since Colonial times. Yet it was not until the 20th century that copper reached the importance of other mining exports such as saltpeter or silver. Before the first world war, saltpeter, collected in Chile from abundant deposits of caliche in the Atacama Desert, was the main source of nitrates in the world. After the World War I, because of the production of artificial nitrates, synthesized first in Germany by the combination of the Haber process and the Ostwald process, the world market for saltpeter, which was Chile�s main export, collapsed. In turn, Chile�s economy became heavily dependent on the copper industry. It was from that period that copper became known as �Chile�s salary�.
By the late 1950s, the three largest copper mines in Chile were Chuquicamata, El Salvador mine, and El Teniente. Chuquicamata and El Salvador were owned and operated by the Anaconda Copper Company. These mines were mainly self-contained and self-sustaining settlements. They were complete with their own cities to house the workers, their own water and electrical plants, schools, stores, railways, and even in certain cases their own police forces. These mines were extremely beneficial in an economical sense, for they provided steady jobs and a steady income for the nation of Chile
