Ohio’s Cuyahoga Valley National Park transformed a toxic wasteland into a natural oasis tucked between Cleveland and Akron, Ohio. “Some say we broke the mold,” Ranger Emily Garrison explains. “While a lot of parks are about protection and preservation, ours is a restoration story.”

The journey was arduous. For over a century, industrial waste congealed in the Cuyahoga River, causing frequent fires. Then in 1969, a train’s spark ignited another bank-to-bank inferno, fueling a movement.

Cleveland’s Carl Stokes, the first African-American mayor of a major U.S. city, called for clean-up help. His prominence helped the plea, spurring environmentalists into action. This, along with a devastating California oil spill, led to the first Earth Day, the Clean Water Act, and the creation of the Environmental Protection Agency.