This subseries contains agreements, correspondence, reports, vital records (such as articles of association and bylaws), and other material from the Boston Office. This includes files from the head offices of the Atlantic Mining Company (and its predecessors) and the Baltic and Trimountain Mining Companies prior to their acquisition by the Copper Range Company.

In the absence of substantial records from the Champion Mine and Mill after William H. Schacht's death in 1944, General Manager W. E. Romig's Painesdale Reports are of particular value, as they provide great detail on the activities of the Mining Division.