Sanborn fire insurance maps were published for insurance companies to assess a structure’s risk of catching fire. They were published in different years for different places, and usually after 1920, a set of maps for a particular town might be updated by pasting over a new building.
The maps show subdivision names, streets, buildings, and building details such as address, purpose, composition, windows and doors. You can locate your ancestor’s address before renumbering and renaming that might’ve happened, and you get a good look at your ancestor’s neighborhood at the time.
Colors indicate construction materials. You’ll find a key on the index map page and more information about the colors and symbols here, along with notes such as the area’s population and size of the fire department.
For genealogists and historians, these maps are an opportunity to get a glimpse into the past. For more information go to: https://www.loc.gov/collections/sanborn-maps/about-this-collection/