 This salt was valuable for a wide variety of purposes, including preserving meats and replenishing what sweating took from humans and animals.Its value made it a commodity used for barter along El Camino Real de Tierra Adentro and was an essential element in the patio process for extracting silver from ore in Chihuahua mines.Historically, caravans to the salt lakes traveled either down the Rio Grande and then straight north or via what became the Butterfield Overland Mail route.