FAQ About Fire Insurance Maps

By Lauren Kuntzman

In honor of Fire Safety Month, in this week’s blog post we’re discussing Fire Insurance Maps (also known as Sanborn Maps). To help you learn how to use Fire Insurance Maps for local and family history research, here are 6 Frequently Asked Questions and their answers.

What are fire insurance maps?

This Key from the Library of Congress collection of

Sanborn Maps shows the meaning of colors and codes

describing building materials and other details.

These maps were made for fire insurance companies to assess their liability within cities across the United States. The maps document factors that could increase or decrease the risk of fire in urban areas. Fire Insurance Maps will indicate…

• Floor plans for buildings, including entrances/exits, proximity of one building to the next, etc.
• Materials used in construction, since wooden structures have a greater risk of fire, as opposed to buildings made from concrete, metal, brick, etc.
• Fire-fighting resources in the area, such as buildings with sprinkler systems, water sources in the area, and if the street was wide enough for fire trucks to drive down.
  
  

Please note: These maps were only created for urban areas, so they will not be available for homes and businesses in rural areas.

Who made fire insurance maps?

The Sanborn Map Company primarily created these maps, but other companies included the Fire Underwriters Inspection Bureau, the General Inspection Bureau, and Rasher Insurance Map Publishing Company. Since so many of the maps were made by the Sanborn Map Company, the name Sanborn Maps is synonymous with Fire Insurance Maps.







How can I use fire insurance maps in my research?

Genealogists and historians use these maps to determine the age of buildings, as well as understand what a building looked like at a specific point in time and what materials were used in its construction. These buildings may include an ancestor’s home or business. 

For example, when looking at the maps for the corner of Broadway and Washington, we can tell that in 1902 the property had a 2-story dwelling, with porches, made from frame construction.

  

Meanwhile, by 1911, the Sylvester Library had been constructed on the property. Its red hue indicated it was constructed from brick, while the open circle meant the building had a slate or tin roof.  

Historians can also use the maps to chart the growth or destruction of a city over time and even reconstruct neighborhoods. Ohio State University is currently using Sanborn Maps in their “Ghost Neighborhoods of Columbus” project. In this project, data from the maps is being used to reconstruct neighborhoods split (or destroyed) by the Interstate Highway system. You can learn more about their project and how Sanborn Maps are being used at https://news.osu.edu/recreating-ghost-neighborhoods-destroyed-by-highways or https://cura.osu.edu/projects/existing/ghost-neighborhoods.

Where can I access fire insurance maps?

These maps can be accessed from many locations online. Here are some resources to try:

• To view black-and-white maps for Ohio cities between 1882 and 1962, https://mcdl.info/OnlineLearning and access the “Sanborn Insurance Maps” database.
• Search for the city, then browse by date.
• To view color maps for Ohio cities from 1882 to 1967, visit Open Access Kent State at https://oaks.kent.edu/sanborn.
• Select the county of interest, then search by city, and browse by date.
• To view color maps for cities from across the USA, visit the Library of Congress’s collection at https://www.loc.gov/collections/sanborn-maps.
• Use the search box at the top of the screen to home in on a particular city, or use the location filters at left to narrow down the collection to a particular state.

How do I navigate fire insurance maps?

Since most cities were too large to fit on a single map, a city and map are often divided across multiple sheets. Each sheet is numbered.  To figure out which sheet in the collection you want to view, start with Sheet #1.  On Sheet #1, look for a Key, as well as an Overview Map and/or an Index of Streets/Business.  

The Key will explain the meaning of the symbols and colors on the maps.  The Overview Map will help you determine which map you need to review for a specific location (note: this feature might only be present with maps that span many, many sheets).  Similarly, the Index of Streets and Business, may help you select a map for a specific address.  

Once you select a sheet to view, you can keep yourself oriented by looking for the sheet's number, typically in the upper right corner. Also, along the edges of the map, it will tell which sheet number the city's map continues onto.  For example, the Sylvester Library is on Sheet #7.  To look one block North on Broadway Street, we see that the map continues onto Sheet #2. 

What other resources can help me understand and use fire insurance maps?

• View a generic Sanborn Map Key at https://www.loc.gov/rr/geogmap/sanborn/images/sankey22c.jpg. 
• Learn more about the history of Sanborn Maps at https://www.loc.gov/collections/sanborn-maps/articles-and-essays/introduction-to-the-collection. 
• Review abbreviations commonly found in Sanborn Maps at https://web.mit.edu/thecity/resources/abbreviations_for_sanborn_maps.pdf. 
• Contact the MCDL Genealogy Team at me-team.genealogy@mcdl.info. We're always happy to try to help answer your questions!