It is today “so common, so easy to obtain, and so inexpensive that we have forgotten that from the beginning of civilization until about 100 years ago, was one of the most sought-after commodities in human history.”

The quote comes from an unlikely best-seller: Mark Kurlansky's Salt: A World History. Humans, of course, have a taste for salt – but it's essential to our survival. Fluid balance, the function of organs and cells – all involve salt. And it's important in preserving foods and tanning hides. Salt has been currency. Its scarcity led nations to war.

At one West Texas place, this resource was available in abundance. For millennia, people journeyed to the Guadalupe Mount...