(DC) (National Portrait Gallery) “Forces of Nature: Voices that Shaped Environmentalism” presents some of the key people—scientists, politicians, activists, writers and artists—whose work has influenced attitudes toward the environment in the United States from the late 19th century until today. The exhibition traces a history of the movement from turn-of-the-20th-century conservationism to mid-20th-century environmentalism and its backlash. It also addresses ...