Humberstone and Santa Laura are located 48 km east of the city of Iquique in the Atacama Desert in the Region of Tarapac� in northern Chile. Other saltpeter works or "nitrate towns" include Chacabuco, Maria Elena, Pedro de Valdivia, Puelma and Aguas Santas among many others. Chacabuco is a special case since it was also used as a concentration camp during Pinochet's regime, and to this day remains surrounded by lost landmines
