I am writing a global history of yellow fever aiming to interrogate the yellow fever story at the global, international, and national levels. Mark Harrison did this for a number of diseases in his recent study of commerce and contagion. Yellow fever has engendered a fund of excellent historical scholarship by Jamie Benchimol, Marcos Cueto, Ilana Löwy, Nancy Stepan, Liora Bigon, and many others. My research at the Rockefeller Archive Center examined materials created before the 1948 founding of the World Health Organization. I wanted to ask, for example, if we ought to think of yellow fever as a global disease. More precisely, when did it become that, if it did? It wasn't long ago that some of our colleagues, especially the more sociologically inclined, chanted the mantra that "All science is local!" This was in some ways a reaction to the historiography of Alexandre Koyré, a Russian émigré working in Paris who coined the term "scientific revolution." He and others enjoined historians of science to focus on theory while others claimed that quantification and replication of results constituted the heart of scientific advance.