Left, The grasslands of Colorado’s Rocky Flats National Wildlife Refuge photographed after cleanup, 2007. The refuge is expected to open to the public in 2018, to the excitement of some local residents and the consternation of others. From 1952 to 1994 the parkland was the site of a nuclear-weapons plant, whose waste contaminated surrounding land and communities. Right, A Rocky Flats worker holds a plutonium “button,” the raw material for the nuclear “triggers” made at the plant, 1973.

U.S. Department of Energy; Library of Congress