In 1970 Marion Edey, a House committee staffer, founded the League of Conservation Voters (LCV) as the non-partisan political action arm of the United States' environmental movement. LCV works to establish a pro-environment—or "green"—majority in Congress and to elect environmentally conscious candidates throughout the country. Through campaign donations, volunteers, and endorsements, pro-environment advertisements, and annual publications such as the National Environmental Scorecard, the League raises voter awareness of the environmental positions of candidates and elected officials.

Technically it has no formal membership, but the League's supporters—who make donations and purchase its publications—number 100,000. The board of directors is comprised of 24 important environmentalists associated with such organizations as the Sierra Club, the Environmental Defense Fund, and Friends of the Earth. Because these organizations would endanger their charitable tax status if they participated directly in the electoral process, environmentalists developed the League...