On June 22, 1969, the Cuyahoga River, which flows through Cleveland, Ohio, caught fire. Although firefighters extinguished the blaze within 30 minutes, the shocking event helped galvanize the U.S. environmental movement. Fifty years later, the river is much healthier but still recuperating from a legacy of pollution, according to an article in Chemical & Engineering News (C&EN), the weekly newsmagazine of the American Chemical Society.