The rise of support for national parks in the United States after 1900 occurred amid a transnational circulation of information on the apparent destruction of – or imminent threat to – nature on a global level. Arguments for creating and protecting national parks included preservation of “wild” areas, proto-ecological ideas, and social reformist and economic utilitarian pressures during the Progressive Era. Advocacy for park protection as it developed to 1916 reflected this complex cluster of ideas rather than any clearly articulated concept of wilderness. It was influenced by international sensibilities on the social construction of nature and its putative preservation at the moment of industrialization in Europe and the American Northeast, the intrusion of mechanization into the countryside and, outside the metropolitan centres of the Euro-American world, high imperialism that exposed widespread destruction of nature in Europe's colonies. The case of the American Scenic and Historic Preservation Society (ASHPS), an elite organization that combined national park, public-park and human-heritage advocacy in a continuum of values, is examined as a transnational conduit for and shaper of these socially constructed ideas in the United States, and as a neglected aspect of Progressive Era development of national parks.