A single folder of correspondence, 1912-1934, contains miscellaneous correspondence and papers concerning primarily the business operations of the firms founded by the McMillan brothers. Only scattered letters are directly to or from either of the two brothers. The correspondence includes statements of federal tax assessments against the Wausau Sulphate Fibre Company; and concerns disputes regarding attorneys' fees, land contracts, timber settlements, and foreclosure actions on California property. After 1926 much of the correspondence is concerned with the settlement of Charles' estate. For 1927, however, there are scattered papers referring to timber cutting privileges on a land tract in Marathon County.
The volumes in the collection contain a nearly complete set of records concerning the McMillans' Wisconsin lumbering operations.
