Maps and Atlas Collection
Sanborn Fire Insurance Company Maps
Maps produced by the Sanborn-Perris Map Company are among the most useful sources for research in environmental, local, urban and architectural history. Originally intended to help insurance underwriters assess city fire risks and set insurance rates, the maps show every structure on selected blocks for some 12000 United States cities and villages. Over 400 of these maps show Wisconsin places, from metropolises like Milwaukee to tiny Victory in Vernon County. Dates range from the1880s to the 1930s.
Drawn usually to a scale of one inch to 50 feet or one inch to 100 feet, these maps show the shape, dimensions, and construction of every building in a block. Colors denote the construction (frame, brick, stone, concrete), and various symbols indicate type or roofing material, locations of doors and windows, and number of stories. Additional codes and printed text explain the use of each building, while many important buildings, including churches, schools, government buildings and major businesses or manufacturing premises are identified by name.
Sanborn maps do not map entire cities, concentrating instead on central business areas where property values and fire risks were highest. Cities were mapped at intervals of several years. Large, fast-growing cities might be remapped at intervals of five years; small villages only once in 10 or 15 years. Because totally re-mapping a large city was costly, maps for the largest places were frequently revised by literally pasting new information on older maps. Maps of larger cities may include maps showing parts of nearby villages or suburbs, which never rated individual mapping. Because much of the Sanborn maps were completed before World War II, place which grew or developed after the 1940s don't appear on the maps.
The periodic re-mapping and revising of Sanborn maps makes it possible to assess the growth of cities, study the evolution of neighborhoods, and even trace architectural changes in a specific building or estimate the date of its construction.
Additional Resources
For more information and sample map images, visit Sanborn Fire Insurance Maps 1867-1950. This article originally appeared in Exchange, a newsletter published by the Wisconsin Historical Society's Office of Local History (Volume 27, Number 3, May/June 1985) and focuses on the value of this resource for studying community history.
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