The LOC.GOV Wise Guide : Safeguard with Sanborn

During the first half of the 19th century, most fire insurance-companies were small and based in a single city. Consequently, the underwriters could personally examine properties they were about to insure. However, as insurance companies became larger and expanded their coverage to numerous cities, a mapping industry developed to support this need. Fire-insurance maps were prepared primarily to assist insurance underwriters in determining the risk involved in insuring individual properties. The Sanborn Map Company of New York eventually came to dominate the insurance-mapping business. Founded in 1867, the firm has issued and periodically updated detailed plans of 12,000 American cities and towns. Some areas are represented by as many as eight different editions. This Library holds some 700,000 large-scale Sanborn fire-insurance maps, in bound and loose sheet volumes.

Insurance Maps of Pittsburg [sic], Pennsylvania. Vol. 2. New York: Sanborn-Perris Map Company. 1893

Division of Maps and Charts, Library of Congress. 1897-1910

Fire insurance maps provide a block-by-block inventory of the buildings in the built-up or congested parts of towns. The outline or footprint of each building is indicated, and the buildings are color coded to show the construction material (pink for brick; yellow for wood; brown for adobe). Numbers inside the lower right corner of each building indicate how many stories the building had, while the numbers outside the building on the street front refer to the street addresses, allowing researchers to correlate these locations with census records and city directories. Individual dwellings are marked with “D” or “Dwg,” but the residents or owners are not identified. Factories, businesses (such as hotels, saloons, liveries), churches, schools and other public buildings (city hall, assay office, library) are labeled by name.

Today, fire-insurance maps are used for a wide variety of research purposes including genealogy, urban history and geography, historical preservation, and environmental studies. The Library accumulated its unsurpassed collection of fire-insurance maps primarily through copyright deposit. In addition, the Bureau of the Census transferred a set of maps updated with pasted-on corrections through to the mid-1950s to the Library in 1967.

The Library’s Geography and Map Division has custody of the largest and most comprehensive cartographic collection in the world, with collections numbering more than five million maps, 72,000 atlases, 6,000 reference works, more than 500 globes and globe gores (designed to be cut out and pasted onto a sphere) and numerous plastic-relief models, and a large number of cartographic materials in other formats, including electronic.

Among the earliest original maps in the collections are three manuscript portolan atlases and 19 portolan charts from the 14th through 17th centuries, drawn on vellum by Italian, Portuguese and Spanish cartographers. The collection of atlases dates from a 1482 printed edition of Claudius Ptolemy's “Geographia” and includes representative volumes of all significant publishers of atlases for the past five centuries. The atlases cover individual continents, countries, cities and other geographic regions, as well as the world ranging in scope from general to topical.

The division also has an excellent collection of manuscript and printed maps of colonial America, the Revolutionary War, the War of 1812, the Civil War and the wars of the 20th century. Supplementing these historical records are photo-reproductions of manuscript maps from various American and European archives. The Hummel and Warner collection include rare manuscript and printed maps and atlases of China, Japan and Korea from the 17th century.

An illustrated guide offers insight into the Library’s Geography and Map Division collection, along with a selection of images of some of its most notable items.

The division has also highlighted several exhibitions relating to geography and cartography. Available for viewing are historical maps of Los Angeles, the map that named “America,” Landsat satellite images (images of the Earth’s surface) and maps documenting the expedition of Lewis and Clark, among others.

A. Insurance Maps of Pittsburg [sic], Pennsylvania. Vol. 2. New York: Sanborn-Perris Map Company. 1893. Geography and Map Division. Reproduction Information: Reproduction information not available.

B. Division of Maps and Charts, Library of Congress. 1897-1910. Prints and Photographs Division. Reproduction Information: Reproduction No.: LC-USZ62-118954 (b&w film copy neg.); Call No.: LOT 9788 [item] [P&P]