The Whiskey Island salt mine in Cleveland is critically important to providing enough road salt to keep streets safe during the harsh winters of the Northeast and Great Lakes states. And it has been a very busy season, with lower temperatures and more snow and ice in many communities served by the salt. The mine is one of the largest salt mines in the world, producing 3 million to 4 million tons per year. But demand can be greater than even that during especially tough winters like the one that mercifully came to a close this month.