This collection consists of records (1876-1974) of the Anaconda Copper Mining Company and contains correspondence, court papers, financial and production records, legal documents, organizational records, subject files, and other materials for the Anaconda Copper Mining Company and many of its predecessor and subsidiary companies and departments. Among the major subgroups are General Office; Big Blackfoot Milling Company; Bitter Root Development Company; Boston and Montana Consolidated Copper and Silver Mining Company; Colorado Smelting and Mining Company; Diamond Coal and Coke Company; Parrot Silver and Copper Company; Reduction Department (Anaconda); Silver Bow Club; Trenton Mining and Development Company; Tuttle Manufacturing and Supply Company; and Washoe Copper Company. In addition, there are more than 100 smaller subgroups.
Oscar Baarson was assistant superintendent of the Anaconda Company's East Helena, Montana, plant; Helena City Engineer; district manager for the U.S. War Production Board during World War II, engineer for the State Examiners Office and Lewis and Clark County surveyor. This collection consists of Oscar Baarson's files (1925-1950) concerning his work with the Anaconda Company, the City of Helena, and the State Examiners Office; and a small group of personal papers relating to Baarson's family, private engineering business, and Masonic activities.