ABSTRACT. Alexander von Humboldt is universally identified as a key figure in laying the foundations for modern geography. His main sites of research and scholarly production were centered on Europe, Latin America, and Russia. He drew on global sources of geographical data and knowledge in constructing and producing his voluminous works. Although he only briefly knew North America firsthand—at the outset of his career, in the late spring of 1804—he maintained a lifelong interest in the realm, especially in the United States. In turn, many North American scholars were admirers and followers of his perspectives, practices, and publications. Although geography did not emerge as an institutionally based discipline in the United States until the late nineteenth century, Humboldt's influence and impact on its antecedents were considerable. Contrary to conventional wisdom, his authority and influence in geography persisted well beyond Humboldt's death in 1859. His vision of demonstrating nature's unity in diversity and his enlightened views on social issues have continued to appeal to select sectors and actors in North American geography, especially Latin Americanists, historians of the discipline, and, more recently, proponents of an engaged, critical geography.