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Home page for the Sanborn maps collection
Home page of Sanborn Map collection

Innovations with Sanborn Maps

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This post is by Jacqueline Katz, the 2022-2023 Albert Einstein Distinguished Educator Fellow at the Library of Congress.

In a recent webinar for teachers, we discussed innovative ways to interact with the Sanborn Fire Insurance Map Collection in the classroom. The recording is now available.

The Sanborn Fire Insurance Map Collection, which is housed in the Geography and Map Division at the Library of Congress and is available online, contains about 700,000 pages of large-scale building level maps. The maps were created by the Sanborn Fire Insurance Company starting in 1867 and continuing to the present day. The map pictured below is one of several made of Princeton, N.J., which is the town where I teach.

Image of portion of map showing part of Princeton, New Jersey
Sanborn Map of Part of Princeton, New Jersey from 1885

Prompt students to observe the map and make some predictions about the meaning of the various colors and symbols. To guide student thinking, you may ask them what factors would be important for a fire insurance company to display on a map. Once students make their predictions, they can check their responses against the key.


Key for Sanborn Map


After student’s familiarize themselves with the map, guide them to focus in on the top left corner. Students can use the Primary Source Analysis Tool to carefully observe this section of the map. Students may ask questions about the labels on some of these buildings, “iron gasometer,” “retorts,” “purifiers.”

Detail from 1885 Princeton ma showing a pond and some buildings
Detail from 1885 Princeton Map

Once students share their observations and questions, research can continue in several different directions depending on the class. In a chemistry class, for example, students may want to consider why the gasometer is composed of iron, but the coal shed made of frame or wood. Students can also explore the relationship between the retort and purifiers in the production of coal gas or hypothesize what type of meter is being used and what it is detecting. In an environmental science class, students could consider the long-term effects of this type of storage on the environment. To connect this historical primary source to the present day, students can visit this location to find evidence of the coal shed’s presence. This could include soil and water quality testing and comparison to other locations around town. Students in either a chemistry or environmental science class could use their findings to determine if the placement of the public school across the street should be reconsidered.

The innovative questions that this 1885 map of Princeton, N.J., inspires are just a small representation of the inquiry that can result from the exploration of Sanborn Maps. To find a map of your town consider using the Sanborn Map Navigator that was created by 2020 Junior Fellow Selena Qian. This navigator allows you to search the collection of digitized Sanborn Maps using an interactive data visualization.

Cover of Sanborn Map Navigator


You and your students can also search for Sanborn Maps using the Sanborn Map Volume Finder. This tool makes it possible to identify present-day addresses within the collection of both digitized and non-digitized maps. Interacting with these innovative search tools can inspire questions from yourself and your students that may not have surfaced with a more traditional review of the collection.

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