Using Sanborn Fire Insurance Maps, 1866-1959

Monday, December 16, 2019

Sanborn maps, fire insurance maps dating 1866-1959, are a valuable research tool. Approximately 3,000 cities have Sanborn maps, covering all 50 of the United States, plus Canada and Mexico.

Sanborn map of Raleigh, 1914, showing Jones Street where the State Library is now located. Sanborn’s North Carolina maps include 145 towns within 85 counties; however, different cities have maps within different years. For example, the town of Hertford in Perquimans County has maps from 1916, 1923, 1929-1940. On the other hand, the town of Concord in Cabarrus County has maps dating from 1885, 1887, 1892, 1897, 1902, 1906, 1911, 1921, and 1927.

Understanding Sanborn Maps

Sanborn maps are highly visual. They contain a lot of information using colors and codes. The Library of Congress has published an online key to the colors and codes you will see on the maps.


Sanborn maps use color to convey information about buildings that would otherwise be unknown. For example, blue identifies stone or concrete-made buildings. Pink represents buildings made of brick or tile. Yellow represents frame (wood) buildings. Some buildings may be constructed from multiple types of material, such as a frame house with a brick front. Colors can be combined in various ways to illustrate showing a frame building with a brick front in Sanborn maps







Codes can tell you several things. See the key for the full list. Below is a list of some common codes:

  • How tall and how many stories a building has
  • Dimensions of a building
  • If the building is constructed with non-flammable material
  • Any special hazards in the building
  • The type of building, such as dwelling, store, or factory

In addition to the codes used for all maps, many have an index on the first page, which list numbers representing different buildings, sometimes with the names of businesses and then corresponding numbers on the map to identify the location of those buildings.

How to Access

There are multiple ways to access Sanborn maps. Repositories such as the State Archives of North Carolina have limited maps you can view in person. There are also online resources to view maps.

The Library of Congress website has the most maps available online and free to view. To date, the Library of Congress has nearly 25,000 images of maps already online. Their goal is to have approximately 500,000 images when all maps are on their site. 

Heritage Quest, which can be accessed through NCLIVE, has Sanborn maps for North Carolina; however, the color has been removed. If you are primarily interested in location (street names, for example), Heritage Quest maps work well for that purpose. But if you want to see all the details, including colors, Library of Congress maps will serve your needs better.

Sanborn maps can provide great information for researchers. Not only can they show where an ancestor lived, but they can also show information on the building in which they live, as well as  the town they lived in and its changes throughout time. These are great tools for research and should not be overlooked.

Erin Bradford, Reference Librarian