Butte's major copper company had many names over the course of its existence. Below is a brief timeline. The "Historical Note" included in the finding aid for the Anaconda Copper Mining Company Records (housed in the Montana Historical Society Archives) offers a concise and very useful corporate history for those wishing more detail.
1880 The Anaconda Gold and Silver Mining Company is formed.
1891 The name changes to the Anaconda Mining Company.
1895 The name changes again to Anaconda Copper Mining Company.
1899 Amalgamated Copper Company is created as a holding company to consolidate the copper industry. Amalgamated owns but is not involved in the management of the various companies, which continue to operate independently.
1915 Amalgamated dissolves and all of its properties become departments of the Anaconda Copper Mining Company.
1955 The corporation changes its name to The Anaconda Company in recognition that its business interests extend far beyond copper.
1971 The Chilean government nationalizes American-owned mines within its borders, bringing about a financial crisis for the Anaconda Company.
1977 Atlantic-Richfield Company (ARCO) purchases the operation.