The Sanborn Fire Atlases, which were compiled starting in 1867 by the Sanborn Map Company, consist of a uniform series of large-scale maps depicting the commercial, industrial, and residential sections of cities and towns in the United States, Canada, and Mexico. The maps were designed to assist fire insurance agents in determining the degree of hazard associated with a particular property and therefore show the size, shape, and construction of dwellings, commercial buildings, and factories as well as fire walls, locations of windows and doors, sprinkler systems, and types of roofs. The maps also indicate widths and names of streets, property boundaries, building use, and house and block numbers.
The Library's Genealogy Collection contains, on microfilm, Sanborn maps for parts of Long Island and New York State. Also, the Patchogue-Medford Library offers Digital Sanborn Maps, an electronic repository of scanned black-and-white versions of Sanborn maps of some Long Island and upstate New York villages, including parts of Patchogue and surrounding areas. The Sanborn Fire Atlases were issued irregularly between 1884-1926 for parts of Patchogue and surrounding areas.