In this article I address the way in which the United States organized the techno-scientific relations with Latin America during World War II and the immediate postwar period. To this end, I analyze the case of the regional research and development program for the cultivation of Hevea (the main source of rubber), implemented by the United States Department of Agriculture (USDA) in Latin America. The research is based on various sources, such as the journal Agriculture in the Americas, USDA documents and articles published by American experts who participated in the program. In dialogue with some contributions from the field of socio-historical studies of science regarding North-South relations at different historical stages. I specifically explore this period, focusing on the devices and institutional arrangements that organized the inter-American techno-scienti-fic relations, the implications they had in terms of the distribution of North-South scien-tific work and information, the main Latin American representatives of the American agencies and the type of knowledge (scientific or not) involved in the program.