Book excerpt: Both Central Park in New York and Yosemite Valley in California became public parks during the tumultuous years before and during the Civil War. Rolf Diamant and Ethan Carr demonstrate how anti-slavery activism, war, and the remaking of the federal government gave rise to the American public park and concept of national parks. The authors closely examine Frederick Law Olmsted's 1865 Yosemite Report--the key document that expresses the aspirational vision of making great public parks keystone institutions of a renewed liberal democracy.