Great Lakes cargo shipments were up again in May.

U.S.-flag ships moved a total of 10.6 million tons of cargo in May, up almost 12% compared to last year and over 8% ahead of the month's 5-year average, according to the Lake Carriers' Association, which represents 13 U.S. companies and their 46 ships.

May 2019 iron ore cargos for steel production totaled 5.6 million tons, an increase of more than 11% from last year.

Coal shipments, which have been falling steadily in recent years, remained similar to last year at 1.4 million tons in May, down 25,000 tons from the year before, or "roughly one cargo of a mid-sized self-unloader," the Association said.

Limestone cargos reached 3.1 million tons in May, up nearly 13% from last year.

Year-to-date cargo sits at 22.4 million tons, an increase of almost 19% compared to the same point in 2018. Iron ore cargos total 13.3 million tons, an increase of almost 14%. Coal loadings sit at 3 million tons, up 33% and limestone cargos have hit 4 million tons, a 20% increase.