Earth Day is a Birthday!! Just like a birthday is a special day to celebrate a person, Earth Day is a special day that celebrates the Earth. Earth Day was born on April 22, 1970, in San Francisco, California. Every year, America and over 100 different countries join together in the celebration of Earth Day on April 22nd. Earth Day is the largest, most celebrated environmental event worldwide. On Earth Day, we remember to appreciate nature and learn ways to protect our environment. Find ways that you can help keep the planet clean and help protect our environment!