Earth Day became a global event with about 200 million participants in 1990.
The 1990 observance marked Earth Day’s 20th anniversary and transformed a largely American environmental commemoration into an international campaign. Events were organized in 141 countries, with people taking part in cleanups, tree planting, demonstrations, educational programs, and recycling initiatives. The scale of participation made environmental issues much more visible worldwide.
Denis Hayes, who had coordinated the first Earth Day in 1970, helped organize the 1990 global campaign. Unlike the original event, which centered heavily on U.S. schools and college campuses, the 1990 anniversary used international networks, television, radio, direct-mail fundraising, and other modern organizing tools.
The campaign also helped build momentum for the 1992 United Nations Earth Summit in Rio de Janeiro. The date is sometimes confused with 2010, when Earth Day organizers reported roughly one billion people taking action for the 40th anniversary. The milestone of 200 million participants belongs to 1990.