What is Earth Day and why do we celebrate it?

Various events are held annually on Earth Day across the globe to show support for protecting the environment.
U.S. Sen. Gaylord Nelson, a Wisconsin native, is largely credited for organizing the first Earth Day in spring 1970, a time when it was still legal for factories to spew noxious fumes into the air or dump toxic waste into nearby streams. That's because the U.S. Environmental Protection Agency didn't exist then, and there were no laws to protect the environment.
Nelson recruited Harvard University professor Denis Hayes to coordinate and promote Earth Day nationally. The event was a success.
Twenty million Americans took to the streets on April 22, 1970, demanding action on environmental pollution. That December, Congress authorized the establishment of a new federal agency, the EPA, to ensure environmental protection. The passage of the Clean Air Act, Clean Water Act, Endangered Species Act and many other landmark environmental laws followed soon after, according to the EPA.
Earth Day went global 20 years later, mobilizing 200 million people in dozens of countries and putting environmental issues on the world stage.
Now, more than 1 billion people in 192 countries are estimated to participate in Earth Day activities every year, according to Earth Day Network, a Washington, D.C.-based nonprofit that organizes the event worldwide.

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