Last updated: 05.07.04 Nadav_Carmel@Brown.edu

A NOTE ON SANBORN FIRE INSURANCE MAPS

The Sanborn Map Company was founded in 1867 and produced detailed fire insurance maps for nearly 100 years. The maps are large-scale plans of a city or town (drawn at a scale of 50 feet to an inch) and contain extensive minutiae used by fire insurance companies to assess risk. These details may include the size, shape and height of a building; the construction materials used; the building's function or goods it produced; ownership information; the location of doors and windows; and the presence of fire precautions; as well as basic information regarding property boundaries, addresses, street names and sizes, limited environmental and topographic features, etc.

The maps generally show every structure present in the year that the map was produced, but only the details of those businesses likely to purchase fire insurance, which most businesses did.

The full map for a given year may be divided into several volumes, each of which is further divided into large numbered sheets. The 1921 Sanborn Fire Insurance map of Providence, for example, is divided into six volumes, each of which contains over 100 sheets.

For this project, the Sanborn Fire Insurance maps were obtained in digital form from Salve Regina University 's McKillop Library in Newport, RI, via their subscription to the ProQuest Information and Learning service's Digital Sanborn Maps. The maps- originally in color- were at some point transferred to black and white microfilm, and it was from these microfilms that the digital versions were created. This loss of information did not affect the project, since only building material was coded by color.

The maps from which the scans were produced for the years 1889, 1900, 1921, 1905, 1921 and 1956 were deposited directly to the Library of Congress; the map from which the scan was produced for the year 1951 is from the United States Census Bureau. A common way to update the maps was to simply paste updates on top of older maps; the maps for the years 1951 and 1956 were updated from the 1921 map in this way.