[a] It was built in 1925 by Great Lakes Engineering Works, Ecorse, Michigan, as the flagship for Cleveland-Cliffs and was named in honor of the then-company president, William Gwinn Mather.

In order to supply the Allied Forces need for steel during World War II, SS William G. Mather led a convoy of 13 freighters in early 1941 through the ice-choked Upper Great Lakes to Duluth, Minnesota, setting a record for the first arrival in a northern port.

All over the vessel, most of the work was supplied by volunteers who repaired, cleaned, chipped, painted, and polished brass in order to restore SS William G. Mather's former elegance.

Due, in large part, to a groundswell of local support to keep the Mather in Cleveland, the Harbor Heritage Society was created to negotiate a new lease agreement with the city.

After ten years of negotiations, the City of Cleveland, represented by Mayor Jane L. Campbell signed a 40-year lease on June 15, 2003, allowing William G. Mather to stay at its East 9th Street berth.