When London had a cholera outbreak in 1854, John Snow and his contemporaries suggested that it was due to a contaminated water pump on Broad Street. But waterborne diseases weren't something people believed as much at the time because the general consensus was that outbreaks spread through miasma or bad air.
Along with results from investigations that had been made, John Snow and others convinced that it wasn't the case and had the pump fixed. After the whole incident, John Snow created the map that would revolutionize data visualization as regards epidemics and outbreaks for more efficient disease prevention.
The simple, yet sophisticated data visualization would lead to radical new ways of conceptualizing disease outbreaks, helping to stop or prevent who knows how many epidemics before they killed hundreds or thousands. Snow’s map also deserves credit for giving “data journalists a model of how to work today.”
(Image credit: John Snow/Wikimedia Commons)