How to Find Fire Insurance Maps
Fire insurance maps were originally produced for the insurance industry to assess the risk of fire and the cost of insurance. A major producer of these maps was the Sanborn Company. The maps were usually at scales of 50 to 100 feet to an inch and included detailed information about residential and commercial buildings such as building material, number of stories, and street address. Other relevant features were also shown such as the type of business and the location of utilities, water pipes, and fire hydrants.
These historical maps provide a unique and valuable look at American cities during the first half of the twentieth century. Publications that provide more information are:
Fire Insurance Maps in the Library of Congress (Gov Pubs Micro/US LC 5.2:F51) identifies the towns and cities of these maps, their original dates of publication, and the latest years of changes made to the original maps.
Fire Insurance Maps : Their History and Applications by Diane L. Oswald (located in 3rd Floor Books at HG9771 .O85 1997).
Map legends are available online from The Sanborn Map Company. See the original legend and the black and white version.
The library owns the original map books for San Diego and select cities as well as a microform collection. For information about fire insurance maps owned by other libraries, see the Western Association of Map Libraries Union List of Sanborn & other Fire Insurance Maps.
The library also owns the original, full-color map books for the cities of Coronado, La Jolla, La Mesa, National City, and San Diego. These are located in Special Collections. See the Special Collections web page for information about hours and policies.
The microfilm collection, located in the Current Periodicals & Microforms Center (1st floor, Love Library), includes the maps of San Diego and a few other cities produced by the Sanborn Map Company between about 1884 and 1970. This microfilm collection is in black and white and so it loses much of the information originally relayed with color (e.g. type of building material). The maps are arranged alphabetically by name of city or town; within each city or town, in chronological order in the order that they appear. They were reproduced from the original copies in the Geography and Map Division of the Library of Congress. Updates were made regularly to original maps, and so the microfiche collection is a snapshot of the maps as they were at a particular time. Fire Insurance Maps in the Library of Congress, listed above, is a useful companion to the set because it gives the original dates of publication and the latest years of changes made to the original maps.