ARCO paid $700 million for Anaconda — and closed a century of Montana mining in six years

The Anaconda Copper Company had been Montana itself for generations — the state's largest employer, owner of its newspapers, a presence in its politics. In 1960 it still employed 37,000 people. On 12 January 1977 the Atlantic Richfield Company, an oil firm, bought Anaconda for 700 million dollars, at the top of the copper cycle.

Then copper fell — to sixty-odd cents a pound — and ARCO decided the business it had bought was not worth managing through the bottom. The smelter in the town of Anaconda stopped in 1980, taking more than 1,000 jobs with it. In 1982 the Berkeley Pit went quiet and the deep pumps of the Kelley Mine were switched off; the Continental Pit, the last active property in Butte, followed. Six years after the purchase, Butte's mines stood completely idle — a camp that had run for a century was closed in five.

The end is kept by the people who worked there: the University of Montana holds the Butte oral-history interviews, and Teresa Jordan's mid-1980s tapes of laid-off miners feed the Verdigris Project's account of the shutdown. Butte's official population — 41,611 in 1920 — had fallen to 33,336 by 1990. The flooded pit and its water became part of the Upper Clark Fork Superfund site, the largest in the United States; the cleanup liability passed, with ARCO's merger into BP, to BP.