Google Earth image
Three mines, producing 80% of the potash in the USA, are in the Carlsbad Basin, in the southeast corner of New Mexico. Potash was discovered here in the 1920s, and underground mining was underway substantially by the late 1930s, when the federal government set aside 43,000 acres to encourage potash mining over other uses. After a boom in production was spurred by demand for explosives in WWII, the Federally Designated Potash Area was expanded to cover nearly 500,000 acres. Over the years mines and processing plants have opened and closed, and mining companies have changed names and ownership. Today two companies own and operate the mines, which have left an interconnected complex of rooms and pillars around 900 feet below the surface, under an area that is around 20 by 25 miles in size.