Dinosaur National Monument straddles the Utah-Colorado border near Wyoming. It attracted little attention and few visitors until plans to dam the Green River and flood picturesque Echo Park Valley sparked public opposition in the early 1950s. That dam, one of a series proposed by the Bureau of Reclamation, was intended to help regulate the Colorado River, generate hydroelectric power, and create a lake for recreation in northwest Colorado.

Echo Park Dam would have threatened part of this national monument, a prospect that alarmed the National Park Service. In July 1950 the writer Bernard DeVoto published his essay "Shall We Let Them Ruin Our National Parks?" in the Saturday Evening Post and spurred nationwide opposition. Soon the Sierra Club, the Wilderness Society, and other organizations embraced preserving Echo Park.

By the spring of 1956 the coalition of wilderness enthusiasts and conservation organizations had faced down the dam's proponents and forced Congress to cancel its construction. As Professor Harvey makes clear, the battle to save Echo Park marked the first major clash between preservationists and developers after World War II, a conflict that replays itself in the West with greater intensity each decade.