Almost a century ago, long before biodiversity expressed a scientific value for nature, Latin American countries began establishing national parks. Today, they represent over 6 percent of Latin America’s landmass. By considering national park creation across a broad regional span and six crucial decades, this article explains a mode of state formation focused on caring for nature instead of just exploiting it. It examines how national parks expanded in the region by identifying three consequent trajectories: the use of these conservation units for frontier development in Argentina and as part of a broader project seeking social justice in Mexico; the formation of more haphazard park initiatives in various countries, taking Brazil and Chile as main examples; and the development of ecologically coherent park systems through the cases of Peru and Colombia. The article also addresses the role of science (especially forestry) and international cooperation in shaping national parks. In this manner, it uncovers the paths that faded from view after the idea that parks intend to protect biodiversity took hold and illustrates a rarely acknowledged aspect of state expansion.