In the decades before the first Earth Day, Americans were living in poor and squalid conditions with pollution running rampant. Large amounts of leaded gasoline were just being guzzled, smoke and sludge being emitted recklessly, and a country unconcerned with a poor environment and human health contributed to growing concerns about the environment and public health. 

All of these conditions were the catalysts for author Rachel Carson to publish her New York Times bestselling book Silent Spring in 1962. Silent Spring sold more than 500,000 copies in over 20 countries. The book highlighted the danger that pollution and squalor posed not only to the environment but also to public health.

This helped shine a light on the issue, and many were moved by Silent Spring; however, no significant policy change has been made yet.

Seven years after the release of Silent Spring, an incident occurred that truly ignited the Earth Day movement. In January 1969, a massive oil spill in Santa Barbara, California, was witnessed by many. Approximately three million gallons of oil were leaked and spread more than 35 miles outward.

To make matters worse, it also heavily impacted the wildlife, killing between 3,700 and 9,000 seabirds. Even after 50 years, with many more terrible oil spills happening during that time, it is still considered the third-largest oil spill in all of U.S. history. 

This undeniably is what influenced U.S. Senator Gaylord Nelson to create Earth Day. He was helped by a young activist, Denis Hayes, and Republican congressman Pete McCloskey. The celebrations took place on April 22nd, 1970, and for the first-ever Earth Day, it did exceptionally well, mobilizing over 20 million people in the U.S. Over the next couple of decades, Earth Day only grew and expanded not just nationwide, but internationally as well.

Now, after 50 years, Earth Day is a global event celebrated in other countries such as the United Kingdom, Denmark, Japan, Australia, and many more.