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By amoats
On July 13, 2020

Lesson Plan: The Power of Geographic Data: The Ghost Map

Description of London in 1854

Steven Johnson describes the sights, sounds and most importantly, smells of London in 1854


In 1854, the London neighborhood of Golden Square experienced a cholera outbreak that killed 1 in 10 inhabitants over the course of 10 days. Public health officials, armed with faulty theories and lacking data made decisions that actually exacerbated the outbreak. Dr. John Snow and Henry Whitehead, a local priest, engaged in a data collection scheme during the height of the outbreak in an effort to prove the real cause of transmission of cholera. Their novel data collection methods and the geographic representation of that data, known as the Ghost Map, led to the elimination of cholera transmission in London and set a standard for the future use of geographic data.


  • Warm-Up:

    Have students answer the following question to begin class.

    • What are different types of data that can be visualized on reference and thematic maps?
  • Introduction:

    Review the Warm-Up by discussing thematic maps that can show everything from population density to bushels per acre of corn produced in a given county. Review types of thematic maps such as choropleth maps and cartograms. Show that reference maps are often used to determine absolute and relative location of physical and political features on the landscape. Both types of maps can be used to solve real-world problems and to make real-world decisions. This lesson will focus on the creation of a map from the 19th century that helped to solve a medical mystery, ultimately saving lives.

  • Exploration:

    Instruct students to view the video clips listed below and to answer the questions in the The Power of Geographic Data - Handout (Google Slides). After students have completed the assignment, discuss their responses as a whole class. Emphasize the living conditions in London in 1854 and how geographic data was used to improve those conditions.

    Organize students into cooperative learning groups. Assign them to complete the comparative sources activity in the The Power of Geographic Data - Handout. Remind students this is an activity in interpretation and analysis. The answers to the questions will not be obvious from the sources provided. Discuss group answers when complete. Reference the Teacher’s Guide (Google Doc) to augment the discussion.


  • Video Clip 1 : Description of London in 1854 (3:07)

    • What were some of the environmental and social challenges facing London in 1854?

    • According to Steven Johnson, which of the five senses would be most affected by life in 1854 London?

    • What were the sources of these sensations?
  • Video Clip 2: The Miasma Theory (2:00)

    • What did the miasma theory identify as the cause of diseases in London?

    • Guided by the miasma theory, what did public health officials do to combat disease in London?

    • How is cholera actually spread?

    • What effect would the acts taken by the public health officials in 1849 have on the spread of cholera?
  • Video Clip 3: Golden Square cholera outbreak - 1854 (4:00)

    • According to research, what do we now know caused the 1854 Golden Square cholera outbreak?

    • Why did people enjoy going to the Broad Street pump? How did this affect the magnitude of the cholera outbreak?

    • What effect did the cholera outbreak have on the Golden Square neighborhood?
  • Video Clip 4: Dr. John Snow (1:22)

    • How did Dr. John Snow’s theory of cholera transmission differ from the miasma theory?

    • How was his theory accepted by his peers and other medical experts?
  • Video Clip 5: Collecting and Interpreting Geographic Data - The Ghost Map

    • How did Dr. John Snow obtain the data he needed to prove his theory?

    • Who was Henry Whitehead and why was he so important in the construction of the Ghost Map?

    • At the request of Dr. John Snow, what did the public health officials do to end the Golden Square cholera outbreak?

    • The Ghost Map was constructed after the Golden Square cholera outbreak ended. What were the lasting effects of the geographic data contained on the map relative to and beyond the treatment and prevention of cholera?
  • Conclusion:

    Have the students answer the following exit ticket questions:

    • In what ways is geographic data being used to solve real world problems today?

    • How have challenges facing humans changed since those faced in London in 1854? How have those challenges remained the same?

    • What is a specific problem facing the world that you feel geographic data and visualization could help solve? How would this data be used to make a change?

Additional Resources


  • Cartography
  • Cholera
  • Effluent
  • Geographic Data
  • Miasma
  • Morbidity


GeographyWorld History


High SchoolUniversity