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Maps Research Guide: Sanborn Maps

A compilation of print and online resources on how to locate and use maps.

Sanborn Fire Insurance Maps Overview

Founded in 1867 by D. A. Sanborn, the Sanborn Map Company was the primary American publisher of fire insurance maps for nearly 100 years.

Sanborn maps were created to assist fire insurance companies as they assessed the risk associated with insuring a particular property. They include information such as the outline of each building, the size, shape and construction materials, heights, and function of structures, location of windows and doors. The maps also give street names, street and sidewalk widths, property boundaries, building use, and house and block numbers.

source: MIT Libraries, Maps: Sanborn Maps Libguide

Why Use It

Color Sanborn fire insurance map of Anaconda Montana

The Sanborn Fire Insurance Maps are a valuable resource for genealogists, historians, urban planners, teachers or anyone with a personal connection to a community, street or building.  The maps depict more than 12,000 American towns and cities.  They show the size, shape and construction materials of dwellings, commercial buildings, factories and other structures.  They indicate both the names and width of streets, and show property boundaries and how individual buildings were used.  House and block numbers are identified.  They also show the location of water mains, fire alarm boxes and fire hydrants. source: News from the Library of Congress, 2017, Sanborn Fire Insurance Maps Now Online

Please visit the Library of Congress Sanborn Fire Insurance Maps website, for additional information on how to read and locate them.

How To Read It

Consult the legend for each map. It is usually found on the first or second page and varies from year to year.

image of 1902 Sanborn map of Missoula

For more information on the difference abbreviations and color coding, please consult the resources listed below.

How to Use Sanborn Maps for Research

For more information on Sanborn maps in Archives and Special Collections, check out this humorous and informative video of Professor of Anthropology Kelly Dixon, explaining how she uses Sanborn maps for archeology purposes.

Mansfield Library's Archives and Special Collections (2015). Banjo Cat: Between Two Ranges Episode 11. Retrieved from https://www.youtube.com/watch?v=cXO71Uvlweo.

How to Access

screenshot of digital sanborn maps homepage

Sanborn maps of Missoula and other Montana cities from 1867 to 1970 are accessible online and in the Mansfield Library.

Digital Access

Physical Access

  • Paper copies of  some Sanborn company maps of Missoula can be found in the map cases on Level 4 in the Montana Room. These maps are organized by year. Each year has its own index that shows the numbered sections of the city and lists streets with the section number they are in. Each index is filed with maps from that year. Years available are 1884, 1888, 1891, 1902, 1912, and 1921. (Archives and Special Collections does not hold a complete set of each year.)
  • Bound volumes of color-coded Sanborn maps of Missoula are available on Level 4 in Archives and Special Collections. Ask at the Montana Room reference desk for more information on how to view them. Years available are 1902, 1921-1931, and 1921-1944.
  • Microfilm Sanborn fire insurance maps of Montana copied from the Geography and Map Division of the Library of Congress are available on Level 1. Call number: 912.782 S198. A guide is available on Level 1 to help you locate the reel you need: Call number: MAP REF 912.786 S198f.

How To Use Sanborn Maps for Family History Research

If you have the street address and house number for where your ancestor lived, you can find out more about them by searching Sanborn maps.

1. Locate maps for that city that were published before, during, and after your ancestor(s) lived there.

2. Find the map sheet with your ancestor's neighborhood. (Use the map index on the first or second page of the volume to help you locate the correct map sheet.) 

3. Find the correct address on the map sheet. This will show the property boundary lines as well as the dimensions and footprint of buildings on the lot. If the map is in color, you can discover details, such as as the building use, construction or whether it had asbestos or fire escapes. Consult the Library of Congress color key for more information.

4. Once you've located your ancestor's residence on the map sheet and studied it for details, examine the sheet for information about the neighborhood. What other kinds of buildings, homes, and businesses surrounded the home? Where there churches or schools nearby? What about factories? This will give you clues to other places you can search for records. If there is a church nearby, do they keep old records? What about a school or business where your ancestor may have attended or a business where they may have worked?

5. Then move on to comparing map sheets of the same neighborhood that were created during different years. This will help you learn more about how the neighborhood evolved. Where streets added or renamed? Was an addition built or an outbuilding converted from a stable to a garage?

These details can help you reconstruct a description of your ancestor's daily life and surroundings.