Sanborn maps are detailed maps of U.S. cities and towns in the 19th and 20th centuries. Originally published by The Sanborn Map Company, the maps were created to allow fire insurance companies to assess their total liability in urbanized areas of the United States.

How often were Sanborn maps made?

For particularly active construction areas, revisions of Sanborn maps were issued at six-month intervals.

Do they still make Sanborn maps?

The last Sanborn fire maps were published on microfilm in 1977, but old Sanborn maps remain useful for historical research into urban geography. The license for the maps was acquired by land data company Environmental Data Resources (EDR), and EDR was acquired in 2019 by real estate services company LightBox.