This research project proposes a systematic analysis and reinterpretation of the Prussian explorer Alexander von Humboldt as a critical figure in the study of the globalization of knowledge through the creation of transatlantic scientific networks. Humboldt’s outstanding impact on the progress of science extended beyond his contribution to particular fields of knowledge: Through his intricate networks with other scholars, established to discuss research questions, exchange data, and compare their results, he also set an early example for a well-organized and fruitful inner-European and transatlantic communication. Of particular importance for this project is Humboldt’s visit to the U.S. in 1804, the contacts he established among its political and scientific leaders, and the vivid interest in the further development of America he maintained for the rest of his life, particularly its progress in sciences and education. The project addresses these core issues through the execution of four closely interlocking sub-projects: First, Humboldt’s North American correspondence will be examined in an in-depth way, which allows for the reconstruction of his scientific network and categorization of his main correspondents, the groups and professions to which they belonged, and the type of information transferred. Second, multiple aspects in which Humboldt promoted German-American scientific collaboration at the beginning of the 19th century will be analyzed. Third, Humboldt’s interest in the western expansion of the U.S. and for California in particular, based on his early research in the Spanish colonial archives in Mexico, will be studied. Finally, the project does not limit its scope to Humboldt; rather, taking him as a starting point and considering the political background of this period, it studies the further development of the scientific relationship between Germany and the U.S. along the 19th century on an individual, institutional and theoretical level.