The social and political unrest in the decade of 1930s, and the Second World War, had a profound impact on the structure of international networks of scientific communication. In the 1940s these nets were redesigned according to the new realities of the world scene. This reconfiguration affected deeply the development of science and of its institutions. In this communication I consider some special circumstances that suggested, in the decade of 1940, the addition of an Inter-American branch to international scientific networks. The consolidation of this last branch had a profound effect on the perception and development of science and of its institutions, in particular of mathematics, in different countries of Latin America. I consider briefly a chain of events that started with a visit George D. Birkhoff, of Harvard University, paid to Mexico, Peru, Chile, Argentina and Uruguay, discussed in more detail elsewhere. Visits of US mathematicians, which had the support of the US Government and of the Guggenheim Foundation, continued and were later extended to Brazil. More importantly perhaps, the Guggenheim and Rockefeller Foundations contributed with their resources to facilitate study-visits of Latin American mathematicians to the US for further training. The wide group of mathematicians involved in these exchanges, the ideology and personality of the architects of this policy, and its impact on mathematics, its practice and, in particular, on its institutions in Latin America are discussed in this communication.