Telling a data story: visualising the spread of cholera with Dr. John Snow 

Necessity is the mother of invention, and in the mid-1800s, understanding the spread of cholera was a matter of life and death.

Cholera was a ruthlessly efficient killer, with both rapid onset and severe symptoms. By the time the disease made its way to London and New York in the early 1830s, hundreds of thousands of people had died across Europe, Africa, and Asia.

Not only our personal and national interests, […] it may be said without exaggeration, [that cholera] concerns the whole human race.

– Thomas Whiteside Hime

Needless to say, the human race was concerned. Thanks to high-speed printing press technology, daily newspaper circulations were rising dramatically, and this allowed journalists to experiment with new reporting techniques, including charting data.

Telling the story of data in the mid-1800s

In 1854, Dr. John Snow was convinced that cholera was spreading via tainted water and decided to display neighborhood mortality data directly on a map. This method clearly revealed a cluster of cases around a specific pump.

The result is one of the most influential maps in modern history, and a fantastic example of how data, used well, can tell a compelling story.

In addition to the real-world utility the map provided in helping physicians understand how cholera was spreading, it also exemplified a seismic shift in thinking that opened up new avenues for data to be analyzed and displayed.

Despite the tragic circumstances of the time period, we can be thankful that the urgency of the situation allowed the world’s pioneering researchers, journalists, and physicians to experiment with new data visualization techniques to better understand the world.