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Learning Beyond the Original Purpose with Sanborn Fire Insurance Maps

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In the November/December 2017 issue of Social Education, the journal of the National Council for the Social Studies, our “Sources and Strategies” article features a 1910 map of South San Francisco, San Mateo County, California. The map was created for the unique purpose of documenting estimated fire hazards, and resides in the Sanborn Map Collection, part of an ongoing digitization project at the Library of Congress. As the Introduction to the Collection notes, “The large file of noncurrent Sanborn maps and atlases constitutes an invaluable historical record of urban growth in the United States over more than a century. Local historians, genealogists and scholars consult the maps today for the wealth of detailed data which they embrace.” A sidebar to the article, excerpted from a post originally published in the Library of Congress blog, describes the collection in more detail.

Image 1 of Sanborn Fire Insurance Map from South San Francisco, San Mateo County, California.

The Sanborn maps document the size, shape, and construction of dwellings, commercial buildings, and factories as well as fire walls, locations of windows and doors, sprinkler systems, and types of roofs. The maps also indicate widths and names of streets, property boundaries, building use, and house and block numbers. Many of them also include notes about available water facilities and fire departments. The featured map comprises ten sheets, including a title sheet featuring a key and a compass rose, a “special index” of major buildings, and a key map – a graphic index indicating which areas are represented on each sheet and which portions of  the city were mapped. The article emphasizes that understanding the key and key map are crucial to gleaning information from the map sheets. .

These richly detailed maps offer many approaches for study and research. Invite students to hypothesize about the economic, social, or strategic importance of a particular place at a particular time. The article focuses on sheets 9 and 10 to prompt research questions. Those sheets document named factories and hotels, offering a starting place for learning more. For example, the Western Meat Company, the Steiger Terra Totta Company,  and the Pacific Jupiter Steel Works are documented in newspapers of the time, available from Chronicling America, and reading about them might prompt students to wonder about manufacturing of the time. Close observation of the path of the railroad tracks might prompt questions, spurring additional research in primary and secondary sources to learn about the role of the railroad in transportation and manufacturing. Other research approaches might emerge from asking:

  • How does this map compare to other maps of the place?
  • How does the purpose of this map dictate the information presented?
  • Who lived in the place?

Finally, the article points to the samplers and time series attached to the collection, suggesting that students might compose their own, perhaps of  a place known to them.

If you engage your students with these maps, let us know what they discovered!

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