Detroit Salt Mine Entrance, Michigan

Salt has been mined from underneath Detroit for more than a century. Most of the mine is located underneath the Dearborn and River Rouge area, where around 100 miles of roads and 1,500 acres of excavated space lie 1,200 feet below the surface. The room and pillar method is still used here, using explosives to blast out the salt, which travels by conveyors underground to the shaft which brings it more than 1,000 feet up vertically in ten ton loads to the surface. The salt is used as winter road salt.