The so-called silver trail, was actually a network of trade routes reaching out from Potosi (in present day Bolivia). Potosi was the world’s largest silver mine in the 17th and 18th centuries, employing over 100,000 workers. Tens of thousands of mule-loads of food and supplies a year were required to sustain what amounted to the largest city in the Americas, at that time Salta (founded in 1582). Thousands of mules lost their lives by slipping over the cliffs or were pulled over by other mules that were tethered. Today the Indians of the region occasionally recover these coins which never made to the coast