"More than 200 million tons of cargo, mostly iron ore, coal, and grain, travel across the Great Lakes throughout the year. Even a little ice can make a big dent on this total. Only three shipments of coal were loaded up during March – 69 percent less, by volume, than last year. A sluggish start to the shipping season is just one of the cascading effects of the Midwest's cold and icy winter. Some are good, and will allow the region to recover from years of historically low water levels. Others, like this delayed shipping season, less so."