Most road salt comes from large underground deposits of rock salt that formed when ancient seas evaporated millions of years ago.

Quick Scoop

  • Road salt is usually rock salt (sodium chloride) mined from underground salt beds.
  • These beds are remains of old oceans that dried up, leaving thick layers of salt behind.
  • Big mines (like the famous ones around Detroit and elsewhere in the U.S.) supply much of the road salt used in North America.
  • In many regions, extra salt is imported from overseas mines in countries such as Chile, Mexico, Egypt, and others.
  • After mining, the salt is crushed to a coarse grain, not purified like table salt, and sometimes treated with anti-caking additives so it flows easily from trucks.

From sea to street (short story version)

Long ago, shallow seas covered huge parts of what is now dry land. Over time, those seas evaporated, leaving thick layers of salt buried under new rock. Miners now tunnel into those salt layers, break out the salt, crush it into chunky crystals, and ship it by truck, train, or ship to storage domes and piles. From there, spreader trucks scatter it onto icy roads every winter to keep tires gripping instead of sliding.

In other words: today’s road salt on your street is ancient ocean salt that’s been mined, crushed, and hauled hundreds or even thousands of kilometers to end up under your car tires.

Information gathered from public forums or data available on the internet and portrayed here.