The History of Earth Day: How a Grassroots Movement Changed the World

Front page of the New York Times from April 23, 1970 featuring an article about the first Earth Day on April 22, 1970

When we think of Earth Day today, we picture community clean-ups, climate marches, and environmental pledges shared online. But the roots of this global movement stretch back to a turbulent time in American history—a moment when concern for the planet collided with a surge of youth activism, giving birth to a day that would change how we think about the environment forever.

The first Earth Day was held on April 22, 1970, and it came to life thanks to the vision of U.S. Senator Gaylord Nelson from Wisconsin. Nelson was deeply disturbed by the environmental degradation he saw around him—oil spills, smog-filled skies, and polluted rivers. Inspired by the energy of the anti-Vietnam War demonstrations, he imagined a national “teach-in” to raise awareness about environmental issues. He enlisted Denis Hayes, a 25-year-old activist, to coordinate the event, and Hayes quickly built a network of volunteers and students across the country.

The response was overwhelming. On that first Earth Day, an estimated 20 million Americans took to the streets, parks, and auditoriums to demand a cleaner, healthier planet. It was the largest demonstration in U.S. history at the time, uniting people across political lines—farmers and urbanites, Republicans and Democrats, students and business leaders. The sheer scale of the event captured the attention of the media and politicians alike, proving that environmental protection was not a fringe issue—it was a national priority.

That early momentum sparked real change. In the years immediately following the first Earth Day, the United States saw the creation of the Environmental Protection Agency (EPA), and the passage of landmark legislation like the Clean Air Act, Clean Water Act, and Endangered Species Act. What began as a single day of awareness quickly evolved into a broader environmental movement that influenced policy and public attitudes for decades.

Earth Day went global in 1990, when Denis Hayes helped organize events in 141 countries. That year marked a major turning point, solidifying Earth Day as an international phenomenon. With the help of satellite TV and growing global environmental awareness, over 200 million people participated. The event helped pave the way for the 1992 United Nations Earth Summit in Rio de Janeiro, one of the largest international environmental meetings in history.

In the decades since, Earth Day has continued to grow in scale and scope. It has become a focal point for activism around climate change, conservation, sustainable development, and more. Themes like “Restore Our Earth” and “Invest in Our Planet” have encouraged individuals, governments, and corporations to step up their efforts. Digital platforms have also amplified the message, making Earth Day one of the most widely observed secular holidays in the world.

Yet, despite its growth, Earth Day has remained true to its roots. It’s still driven by everyday people—students organizing rallies, communities planting trees, and citizens advocating for change. The spirit of grassroots activism that sparked the first Earth Day continues to thrive, reminding us that collective action can have a powerful impact.

More than just a day on the calendar, Earth Day is a call to action—a reminder that we share one planet and that our choices matter. Whether it’s turning off the lights, voting for green policies, or simply spreading awareness, every action counts. Earth Day’s history is a testament to what we can achieve when we come together to protect the world we call home.