Taking as its subject the production of architectural discourse in the 19th- and early 20th-century United States, “Nature and Nation” examines how ideas emerge from, depend upon, and shape the way human societies understand and transform the natural world. To do so, it articulates two distinct questions, one methodological and the other historiographical: Do architectural ideas have an environmental history? How did changing environmental conditions shape American architects’ understanding of national history? Focusing on a historical sequence spanning from roughly 1840, when emerging ideas of nature endowed with a ‘national’ character coincided with the first expression of a ‘national’ architecture in the United States, to 1940, when the disaggregation of such ideas of nature accompanied the advent of the International Style, “Nature and Nation” illustrates the mutually constitutive character of architectural ideas and environmental conditions. By examining the writing of architects, mapping the theoretical lineaments of the ideas they formulate, and identifying the points of friction that arise from the experience of hostile climate, adverse soil conditions, material scarcity, pollution, and other human-induced phenomena, it shows how the experience of changing environmental conditions shaped American architects’ understanding of national history.