North of Van Horn, and on the western boundary of the Guadalupe Mountains National Park are salt flats. They appear white, stark in contrast to the surrounding desert vegetation. You can visit them today, along Hwy 62.
The nearly pure white salt supplied people in all of West Texas, southern New Mexico and Mexico, and citizens on both sides of the border collected the salt for free, until a series of bloody incidents culminated in the "Salt War" of 1877. You can read about these conflicts at Borderlands, a website of local history at El Paso Community College. There is also a fine exhibit about the Salt War at the Los Portales Museum and Information Center at San Elizario.
While visiting the National Park, take a little detour to the west. You'll be rewarded with a sight not often seen--pure white salt!