Researching Historic Homes & Buildings: Insurance Maps

Library of Congress Sanborn Map Collection - The Library of Congress website contains a wonderful key and explanation of how to interpret the maps. A small portion of the maps in their collection are available in color. 

Digital Sanborn Maps - Available at Wyoming libraries through the GoWyld.net portal. This collection contains black and white scans of the 660,000 Sanborn Insurance Maps in the Library of Congress' collection. 

Wyoming State Archives - The WSA houses a small collection of Sanborn Insurance maps, some in color and some in black and white for towns across Wyoming. Some of these have been scanned and are available in the online map collection database. 

Local Libraries and Museums - Copies of insurance maps may be found in local libraries and museums.

College and University Libraries and Archives - Copies of insurance maps may be found in college and university libraries and archives. In Wyoming, examples can be found at the University of Wyoming's American Heritage Center and Casper College's Western History Center, among others. 

Old House History online article about Using Historic Fire Insurance Maps

Where should I look?

Check with your local City Engineer's office or the local County Clerk's office.

Insurance maps were created or commissioned by insurance companies to help them calculate the risk, and thus the cost, of insuring a property. 

These maps included information about the size of the building, construction materials, number of floors, the location of exterior doors, and windows, stairwells and skylights and the building's use. All of this information contributed to the insurance company's appraisal of the property and its fire risk. 

Today, these maps can be used when researching historic properties. The maps can provide clues to narrow down construction dates, dates of additions and possible demolition dates.  They also tell you a lot about your neighborhood, whether or not it was always residential, how it has built up, etc.

Cheyenne Sanborn Map, March 1890 (from the Library of Congress Sanborn Map Collection website)

(from the Library of Congress Sanborn Map Collection website)

The insurance maps used a system of standard symbols and colors to describe the characteristics of the properties. The Library of Congress has put together a wonderful explanation on their website.