Earth Day is an annual event celebrated around the world on April 22 to demonstrate support for environmental protection. First celebrated in 1970, it now includes events coordinated globally by the Earth Day Network in more than 193 countries.In 1969 at a UNESCO Conference in San Francisco, peace activist John McConnell proposed a day to honor the Earth and the concept of peace, to first be celebrated on March 21, 1970, the first day of spring in the northern hemisphere. This day of nature's equipoise was later sanctioned in a proclamation written by McConnell and signed by Secretary General U Thant at the United Nations. A month later the United States Senator Gaylord Nelson proposed the idea to hold a nationwide environmental teach-in on April 22, 1970. He hired a young activist, Denis Hayes, to be the National Coordinator. Nelson and Hayes renamed the event "Earth Day". Under the leadership of labor leader Walter Reuther, the United Auto Workers was the most instrumental outside financial and operational supporter of the first Earth Day. According to Hayes, "Without the UAW, the first Earth Day would have likely flopped!" Nelson was later awarded the Presidential Medal of Freedom award in recognition of his work. The first Earth Day was focused on the United States. In 1990, Denis Hayes, the original national coordinator in 1970, took it international and organized events in 141 nations.On Earth Day 2016, the landmark Paris Agreement was signed by the United States, China, and some 120 other countries. This signing satisfied a key requirement for the entry into force of the historic draft climate protection treaty adopted by consensus of the 195 nations present at the 2015 United Nations Climate Change Conference in Paris. Numerous communities celebrate Earth Day Week, an entire week of activities focused on the environmental issues that the world faces.