Earth Day, an event to increase public awareness of the world’s environmental problems, is celebrated in the United States for the first time on April 22, 1970. Millions of Americans, including students from thousands of colleges and universities, participated in rallies, marches, and educational programs across the country. Earth Day was the brainchild of Senator Gaylord Nelson of Wisconsin, a staunch environmentalist who hoped to provide unity to the grassroots environmental movement and increase ecological awareness. “The objective was to get a nationwide demonstration of concern for the environment so large that it would shake the political establishment out of its lethargy,” Senator Nelson said, “and, finally, force this issue permanently onto the national political agenda.” The 1962 publication of Rachel Carson’s book Silent Spring—about the effects of pesticides—is often cited as the beginning of the modern environmental movement in the U.S. Sustainability, organic eating, and the “back-to-the-land” movement continued to gain steam throughout the 1960s. The first Earth Day indeed increased environmental awareness in America, and in July of 1970, the Environmental Protection Agency was established by special executive order to regulate and enforce national pollution legislation. Earth Day also led to the passage of the Clean Water and Endangered Species Acts. On April 22, 1990, the 20th anniversary of Earth Day, more than 200 million people in 141 countries participated in Earth Day celebrations. Senator Nelson was awarded the Presidential Medal of Freedom by President Clinton. (He died in 2005.) Earth Day has been celebrated on different days by different groups internationally. The United Nations officially celebrates it on the vernal equinox, which usually occurs about March 21. Earth Day 2021—the 51st anniversary—is celebrated on April 22.