Beneath the soaring western escarpment of the Guadalupe Mountains, geologic and chemical forces combine to create a resource humans have sought since civilization began: salt.

Indigenous peoples made salt expeditions here for millennia. Spanish invaders sent wagon trains to gather salt for mines in Chihuahua. But in the late 19th century, the Guadalupe Mountains Salt Lakes became a flashpoint in a violent conflict. Echoes of the San Elizario Salt War continue to sound today, and its traces are etched in the West Texas landscape.

Today, San Elizario is a small, if growing, community on the Rio Grande, downstream of El Paso. But in the mid-19th century, it exceeded El Paso as a cente...