New online resource excites genealogists, urban planners, and others

August 20, 2013
Credit: Penn State University Libraries

Rich with valuable and detailed information, Sanborn Fire Insurance Maps—originally created more than a century ago as a product to help insurance companies assess the potential risks involved in underwriting policies—have developed into a tool with myriad uses by researchers in multiple fields. These maps provide extensive details about the roads and buildings in cities and towns throughout the United States. Genealogists, architects, urban planners, and historians have long prized the impressive detail, clear printing, multiple editions (showing changes over time), and distinctive style that mark these maps. Whether tracing turn-of-the-century city expansion, looking for the home of an ancestor, or researching boundaries and zoning ordinances, the Sanborn maps are a key source of reliable data.

While the vast majority of the collection consists of individual, unbound sheets, maps for some of the more industrialized areas and largest urban areas were published as bound volumes. Most communities have multiple editions, each edition being a specific date of publication that provides a unique perspective on community growth over time.

Recently Penn State's University Libraries completed the cataloging and digitization of the entire collection of Sanborn maps that span the late 19th and early 20th centuries—31,036 sheets, representing 585 large and small communities across the Commonwealth. Titles published before 1923 and available online to the public are presented in an alphabetical index of Pennsylvania communities at As copyright restrictions are lifted for post-1922 titles, the scanned images of those communities also will be mounted on the Maps Library's Sanborn Fire Insurance Maps website for use.

The physical map collection, housed in the Donald W. Hamer Maps Library in Pattee Library, does not circulate but may be viewed and used for research within the Maps Room. Titles can be found in The CAT, the Libraries' online catalog, by conducting a keyword search of "Sanborn" plus the desired community name, and limiting the search to the "Maps Library" location. Copies may be obtained for individual sheets with the assistance of the Maps Library staff.

Surveyor D.A. Sanborn founded the company in New York City in 1867 to create special maps, most often at a scale of 1:600, or 50 feet to the inch, to aid companies in assessing liability for fire insurance coverage of buildings in communities across the United States. Teams of surveyors infused the maps with a remarkable level of detail, and for most cities and towns new editions were published every few years, providing a fascinating and unique snapshot into community and industrial growth. The sheets that cover each community accurately show the location of buildings and outbuildings, including details such as where windows and doors are positioned, as well as property boundaries, the names of land and company owners, the width of streets and sidewalks, building use and, most importantly, the construction materials used for homes, businesses, and other buildings. Key local industries were sometimes highlighted with inset maps, and textual notes added useful information such as the type of water supply and firefighting equipment and companies available. Other useful tidbits of information found on these maps include population figures, street and building indexes, and even prevailing winds!

Originally called the D.A. Sanborn National Insurance Diagram Bureau, the company went through several name changes. It was incorporated in 1876 as the Sanborn Map and Publishing Company, and after acquiring rival Perris and Browne in 1899, it was known as the Sanborn-Perris Map Company, Ltd., thus allowing it to trace its lineage to the year 1852. The name was later shortened in 1902 to its best-known moniker, the Sanborn Map Company.

Explore further: Five centuries of North Carolina maps posted online

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