Earth Day is an annual event on April 22 to demonstrate support for environmental protection. First held on April 22, 1970, it now includes a wide range of events coordinated globally by EARTHDAY.ORG (formerly Earth Day Network)[1] including 1 billion people in more than 193 countries.[2][1]

The original idea was for a teach-in to include the entire United States. More than 20 million people poured out on the streets, and the first Earth Day remains the largest single day protest in human history. ...   On Earth Day 2020, over 100 million people around the world observed the 50th anniversary in what is being referred to as the largest online mass mobilization in history.  (source: Wikipedia)