On June 20, 1969, the Cuyahoga River in Ohio caught fire.

It wasn't the first time: At least a dozen other fires, sparked by pollution in the water, broke out on the river in the late 1800s and 1900s.

The 1969 fire was quickly extinguished, but it prompted political action that led to the creation of the US Environmental Protection Agency in 1970.

Here's what the river looked like before pollution was regulated.

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Fifty years ago, on June 22, 1969, the Cuyahoga River in Cleveland caught fire.

At the time, the river was one of the most polluted in the US. Journalists filled glasses with pitch-black river water, while politicians dipped cloth into the waves that came up oil-soaked.

The river fire lasted roughly 20 minutes, but it sparked public outrage that in part led to the creation of the US Environmental Protection Agency, the federal office tasked with making sure "Americans have clean air, land, and water."

Take a look at what the Cuyahoga River — and other waters around the US — looked like before the EPA existed.