Shipments of limestone on the Great Lakes totaled 28,153,642 net tons in 2011, an increase of 1% over 2010, but a decrease of 10.2% compared to the trade’s 5-year average. At 23,121,059 tons, shipments from U.S. quarries increased 3.5 percent compared to a year ago, but were 7.9% off the trade’s 5-year average. At 5,032,583 tons, loadings at Canadian quarries slipped by 9.3% compared to a year ago, and fell even further – 19.4% – when compared to the trade’s 5-year average.

A major portion of the limestone shipped on the Great Lakes is aggregate for the construction industry. Lakes-shipping quarries also supply U.S. and Canadian steelmakers with fluxstone that is used as a purifying agent in the steelmaking process. Although some blast furnaces have been restarted, the industry is still operating below capacity.

U.S. ports include: Calcite, Cedarville, Drummond Island, Port Inland and Presque Isle, MI., and Marblehead, Ohio.  Canadian ports include: Bruce Mines, Manitoulin Island, and Smelter Bay (all Ontario). 

Lake Carriers’ Association represents 17 American companies that operate 56 U.S.-flag vessels on the Great Lakes and carry the raw materials such as iron ore and fluxstone for the steel industry, aggregate and cement for the construction industry, and coal for power generation.  Collectively, these vessels can transport more than 115 million tons of cargo a year when high water offsets lack of adequate dredging.