Sanborn fire insurance maps - established as the D.A. Sanborn National Insurance Diagram Bureau by Daniel Alfred Sanborn in 1867 - have long been used by researchers in a variety of ways. As they were "created to allow fire insurance companies to assess their total liability in urbanized areas...they contain detailed information about properties and individual buildings [and] are valuable for documenting changes in the built environment of American cities over many decades." For example, in addition to residential dwellings and civic buildings (e.g. City Hall, schools, jails), Sanborn maps also show the location of a variety of businesses, including liveries or stables, boarding houses and hotels, saloons and breweries, bakeries and blacksmiths, drug stores, jewelry stores, photography studios, grocers, and even brothels.

However, Sanborn maps are unique in that they often report on other types of demographic information of interest to researchers. For example, sheet one of the Sanborns for Roseburg, Oregon in 1885, notes the location of two Chinese "wash houses" (i.e. laundries) on Jackson Street; a dwelling at the corner of Douglas Avenue and Jackson Street notes that the residents are Chinese. Sheet one of the Sanborn maps for Roseburg in 1888 notes the location of a Methodist church on Washington Avenue; sheet two notes the location of a Catholic church at the corner of Kane Street and Oak Avenue; Episcopal and Methodist churches on Main Street; and a Presbyterian church on Rose Street.

Sanborn Fire Insurance Maps of Oregon, 1879-1956
The Sanborn Fire Insurance Maps of Oregon are an extensive collection of detailed maps of 178 towns and cities in Oregon prepared for the primary use of insurance companies. The bulk of the maps were prepared in the 1880s through 1920s. The maps depict both business and residential areas and provide detailed information about the location and type of construction of structures. Most of the maps are at a scale of 1 inch = 50 feet. The collection includes maps of Portland, Astoria, Bend, Corvallis, Eugene, Medford, and Salem as well as numerous smaller towns and villages. All types of structures are represented, including homes, apartments, and boarding houses; churches; schools, courthouses, community halls, parks, playgrounds, and other public facilities; warehouses, factories, mills, dryers, canneries, and creameries; retail stores, banks, and other businesses; and garages, barns, and sheds. The maps provide detailed information about lumber and saw mills and log ponds. Information about streets and railroads as well as the water system and fire department for each municipality are provided on the maps. The Sanborn Maps indicate the type of construction of each structure, whether it is wood, brick, stone, or a combination; the size of the structure and number of floors; and the heating source.

The Library of Congress has made a selection of their Sanborn maps available online.