It is reached from the Pacific by way of Challapata, a station on the Antofagasta & Oruro railway.
Chile saltpetre, cubic nitre or sodium nitrate, NaNO,, occurs under the same conditions as ordinary saltpetre in deposits covering immense areas in South America, which are known locally as caliche or terra salitrosa, and abound especially in the provinces of Tarapaca and Antofagasta in Chile.
It was formerly capital of the Bolivian department of Atacama and the only port possessed by Bolivia, but the seizure of that department in 1879 by Chile and the construction of the Antofagasta and Oruro railway deprived it of all importance, and its population, estimated at 6000 in 1858, has fallen to less than 500.
Smelting for neighbouring mines is still carried on, and some of its former trade remains, but the greater part of it has gone to Tocopilla and Antofagasta.
Antofagasta is the seaport for a railway running to Oruro, Bolivia, and is the only available outlet for the trade of the south-western departments of that republic. The smelting works for the neighbouring silver mines are located here, and a thriving trade with the inland mining towns is carried on.