Dr. John Snow’s Cholera Dot Map of Soho (1854)
"The foundational map of spatial epidemiology proving the waterborne origin of cholera"
During the September 1854 cholera outbreak in Soho, London, Dr. John Snow plotted each cholera death as a black bar stacked at the victim's street address. The spatial clustering revealed that deaths concentrated around the Broad Street water pump.
- Black bars representing deaths stacked outside residential doorways
- Broad Street pump situated at the exact geometric center of death clusters
- Voronoi-like walking distance polygons showing the pump was the closest water source
Image credit and reuse
Dr. John Snow’s Cholera Dot Map of Soho (1854)
John Snow; via Wikimedia Commons
Public domain under the individual source record. Metadata added; image pixels unchanged. Display crop may vary by viewport. Retain source credit and terms. Historical mapmaking context is separate from this image reproduction.
The Rhetorical & Ideological Argument
"Cholera is not transmitted through airborne 'miasma' or moral degeneracy; it is a waterborne pathogen whose source can be proven by spatial clustering around contaminated infrastructure."
- Black bars representing deaths stacked outside residential doorways
- Broad Street pump situated at the exact geometric center of death clusters
- Voronoi-like walking distance polygons showing the pump was the closest water source
- Architectural floor plans and socio-economic demographics