John Snow (British, 1813–1858) helped found epidemiology, the study of the distribution and causes of disease. In the 19th century, many people believed that cholera was caused by the unhealthy habits of people living in poverty. Snow’s scientific maps proved that contaminated water—not dirty air or an immoral lifestyle—caused the spread of cholera.

Driven partly by Snow’s research, modern urban sewage systems were created to prevent the spread of diseases like cholera. Today, sewage systems can be monitored for data about disease outbreaks, including COVID-19.

Content from the exhibition Design and Healing: Creative Responses to Epidemics, curated by MASS Design Group and Cooper Hewitt, Smithsonian Design Museum


Distribution of Cholera Cases in Soho, London, 1854
John Snow’s map shows multiple cases of cholera clustering around a particular water pump, proving that water carries this disease.

View of map of London showing city grid and clustered dotted areas

Map: John Snow, On the Mode of Communication of Cholera


Water Supply of the Southwark and Vauxhall and Lambeth Companies, London, 1855
This map shows neighborhoods supplied by two different water companies. People consuming water from the Southwark and Vauxhall Company (blue) became ill with cholera, while those consuming water from the Lambeth Company (pink) did not. Thus, the water supply, not social class or behavior, caused the disease.

Gray map of London with two overlapping amorphous areas in red and blue

Map: John Snow, On the Mode of Communication of Cholera

Featured Image: Map: John Snow, On the Mode of Communication of Cholera

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