Clue 1: As a senator from Wisconsin, I came up with the idea for Earth Day.
Clue 2: The first Earth Day was celebrated on April 22, 1970. More than 20 million people participated.
Clue 3: I left the Senate in 1981, but I remained involved in conservation issues. In 1995, I was awarded the Presidential Medal of Freedom for my environmental efforts.
Who am I? _________________