With its magnificent forests, bluffs, and shoreline and its breathtaking views of Green Bay and Lake Michigan, Door County’s Peninsula State Park is one of the Midwest’s most popular attractions. Established in 1909, it was Wisconsin’s second state park and a key to pioneering efforts to build a state park system that would be the envy of the nation. Door County’s Emerald Treasure explores the rich history of the park land, from its importance to Native Americans and early European settlers through the twentieth century. Bill Tishler engagingly relates the role of conservationists and progressives in establishing the state park, its growing popularity for tourism and recreation, and efforts to protect the park’s resources from a variety of threats. Tishler also tells a larger story of Americans’ intimate relationship with the land around them and the challenge to create accessible public spaces that preserve the natural environment.