The Detroit and Lake Superior Copper Company Records contain correspondence, financial records, and reports of General Managers John R. Grout and James R. Cooper and Chief Clerk Z. W. Wright. It includes records from its predecessors, the Waterbury and Detroit Copper Company and the Portage Lake Smelting Works, as well as its successors, the Lake Superior Smelting Company and the Tamarack-Osceola Copper Manufacturing Company.

Note that the records of the Detroit and Lake Superior Copper Company are split between this series and MS-043, Keweenaw Historical Society Collection. Researchers are encouraged to consult both collections.