Kenneth Field explores (and dismantles) the mythology around John Snow, the discovery that cholera was spread by water, the role of the famous cholera map and whether it revolutionized disease mapping. Depending on what you know about the subject—if, for example, you got what you know from an episode of Map Men—what you know is more myth than history: the map came after the Broad Street outbreak, it was not by any means the first example of disease mapping, and John Snow wasn’t the map’s cartographer. Field:

The mythology surrounding his work, the 1854 epidemic, and specifically the role of the map are a fine story, but much of it is retold according to the version many seem happy to believe rather than what really happened. But the real story is just as interesting. There are plenty of excellent longer form discussions of the story in which you may be interested. In particular, Kari McLeod’s excellent article that goes into detail about the various myths, and an article by Tom Koch and Kenneth Denike also goes into detail about the true order of events.