The industrial revolution in the 1700s brought with it a plethora of novel public health issues stemming from rapid urban development and poor sanitation, conditions which fueled the development of disease mapping, or medical cartography. A precursor to medical geography, medical cartography arose from the need to communicate spatial discrepancies in risk for diseases of unknown cause, particularly urban outbreaks of cholera and yellow fever. One of the most prominent figures in both epidemiology and medical geography is John Snow, the physician who correctly identified the source of exposure during the 1854 Broad Street cholera outbreak. Snow’s famous 1854 map of the cholera outbreak graphically demonstrates that cases were clustered around the Broad Street pump, the source of contaminated water that fueled the epidemic. This map led Snow to identify the contaminated pump and conclude that cholera was a waterborne illness, a remarkable feat given that bacteria were unknown to science at the time. While Snow’s contributions to medical geography and epidemiology are irrefutable, the role of the map in this particular investigation is somewhat overstated. Dot maps of cases produced during the industrial period were powerful tools in communicating the findings of traditional epidemiological measures of association, but their role as analytic tools were restricted due to technological limitations.