They were declared a UNESCO World Heritage Site in 2005, as a testament to the historical importance of saltpeter mining in Chile and the culture and social agenda that developed around it in the late 19th century.

[4] Humberstone and Santa Laura are located 45 km east of the city of Iquique in the Atacama Desert in the Tarapacá Region in northern Chile.

[3] Other saltpeter works or "nitrate towns" include Chacabuco, Maria Elena, Pedro de Valdivia, Puelma and Aguas Santas.

In 1872, the Guillermo Wendell Nitrate Extraction Company founded the saltpeter works of Santa Laura, while the region was still a part of Peru.

However the economic model collapsed during the Great Depression of 1929 because of the development of the synthesis of ammonia by the Germans Fritz Haber and Carl Bosch, which led to the industrial production of fertilizers.