Transportation agencies across the country have put down a lot of salt on the roads this winter, due to some severe conditions. Numbers for this year have us on track to use a record amount of salt over the snow/ice season. While some states are scrambling to round up enough salt to meet their needs, others say they have a glut of it; like Michigan, who has a giant salt mine under the city of Detroit. First tapped in 1914, the mine has a facinating history. In fact, the history of salt being used on roads in general is pretty interesting, as evidenced by this National Geographic article on the history of road salt (if anyone can make a potentially dull topic interesting, it’s National Geographic).