Idaho Sanborn Maps

Contents: About the Collection | About the Sanborn Maps | Tech

About the Collection

The Sanborn Maps digital collection contains 198 insurance maps (about 1,200 individual map pages) of Idaho towns created by the Sanborn Map Company.

The maps contain detailed information, such as the location and dimensions of each building. The Sanborn maps also include street names, locations of fire hydrants and water and gas lines, railroads, and even natural features like rivers, lakes, and ditches.

The maps can be interpreted using the following color key, which indicates the building materials, stories, interior walls, windows and structure of each building.

For example, buildings colored red are made of brick, and the structures in yellow are frame buildings. Special fire hazards in buildings are colored green and marked with either an “x” or a dot.

Most structures are denoted by an abbreviation that indicates what activity occurred at that particular structure. The guide below from MIT was used to extract this information to create the subjects field. This metadata work is ongoing.

For more information on how to interpret the Sanborn Maps, please refer to the Library of Congress Guide.

The U of I Library Special Collections and Archives houses all of the Idaho Sanborn maps from about the 1880s until the 1930s. The digital collection of these maps makes them more widely available for the variety of researchers interested in the history of Idaho towns and the structures within them, while also preserving these historical documents.

About the Sanborn Maps

The Sanborn Map Company was founded by D.A. Sanborn in 1867 in New York City. Sanborn began as a surveyor for the insurance maps in Boston and from there worked with the Aetna Insurance Company in Tennessee.

After making these insurance maps for these cities, he realized how important these maps are for fire insurance companies, so he established his own industry creating these maps for fire insurance purposes. D.A. Sanborn died in 1883, but his company only grew in popularity and thrived for many more years.

The Sanborn Fire Insurance maps continued to produce these maps for fire insurance companies so they assess their liability in towns and cities across the United States, Canada and Mexico.

The Sanborn Maps started to be replaced by line carding in about the 1950s. However, the maps now are a rich source of historical data and used by many different people.

Researchers use these maps to study patterns of growth and change within the various towns and cities as well as how specific buildings may have changed over time. Historic preservationists use the maps to assess the significance of old buildings and understand the building uses and how they may have changed over time. Archaeologists use them to trace the history of locations of excavation sites to understand the material culture found at the site. Environmental site assessors use the maps to inspect sites for certain conditions and to help with planning potential projects. Genealogists even consult the maps to trace their ancestors’ locations.

Sources

The Library of Congress, “Introduction to the Sanborn Map Collection,” accessed August 31, 2023, https://www.loc.gov/rr/geogmap/sanborn/san4a1.html