The Great Lakes provided the vital link between Michigan's copper
district, three iron ranges and the rest of the world. Boats brought people and supplies
to Michigan's Upper Peninsula mine industry ports: Marquette, Copper Harbor, Escanaba.
They carried copper ingots and iron ore to smelters and markets near Chicago, Detroit, and
Cleveland.
 The Sault Ste. Marie (Soo) Canal opened in 1855. By
eliminating the need to portage cargoes around the St. Marys River Rapids, it reduced
shipping time and costs. In the photograph a "whaleback" ore carrier goes
through the Soo Locks.
The Portage Lake and Lake Superior Ship Canal was cut through the Keweenaw Peninsula
in 1873 to further reduce shipping time. In winter, the docks were often piled high with
ingots waiting for spring and the return of the ships. After a rail connection to the
region was completed in 1877, copper was transported year-round.
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