Silver, iron and other minerals have drawn miners to the Great Lakes region for more than 7,000 years, but it is pure, elemental copper that inspired dreams of riches. Prehistoric tribes and native Americans were the first to extract the ore, followed by French missionaries, fur traders and the British. In 1842, the newly formed United States government opened Michigan’s Keweenaw Peninsula to settlement and mining, and in 1846, the Quincy Mine began operation. Several others opened over the next 25 years, and by 1900, the U.S. was the world’s largest copper exporter.

After World War II, mining operations were increasingly not competitive with strip mining in the western U.S. and foreign markets such as Australia, Chile and Bolivia. The Quincy mine ceased underground mining in 1945 but continued to process remaining ore until 1976. By the mid 1950s, other large mines, such as Calumet & Hecla, closed. The last active copper mine in the Great Lakes region closed in 1996.

The mining industry’s legacy is an immense, underground labyrinth that provides a perfect, constant temperature for hibernating bats. However, in the late 1980s and early 1990s, there was a push to close old, abandoned mines due to safety risks. Unaware of how critical these mines had become as bat habitat, millions of bats were destroyed as mines began to be permanently sealed.