The Sanborn Map Company, Inc., was formed in 1876. The company's purpose in producing finely detailed maps of cities was described in their
1905 Surveyor's Manual for the Exclusive Use and Guidance of Employees , "Our maps are made for the purpose of showing at a glance the character of the fire-insurance risks of all buildings. [Fire insurance functionaries] depend on the accuracy of our publications...incurring large financial risks without making personal examinations of the properties."
From an article in
Historic Preservation by Kim Keister (May/June 1993, pp. 42-49; 91-92) many researchers use them, though not for their original purpose of fire insurance. "Simply stated, the Sanborn maps survive as a guide to American urbanization that is unrivaled by other cartography and, for that matter, by few documentary resources of any kind."
The microfilmed maps in this collection are housed by the Library of Congress' Map & Geography Division.
