Historical Research Maps: Sanborn Fire Insurance Maps

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Fires have long been a foe to genealogists, destroying courthouses and the records inside them. But fire has also been the impetus for the creation of a valuable record set: Sanborn fire insurance maps.

The Sanborn Map Co. created maps to evaluate potential fire hazards in communities. As a result, these maps (named after the company) provided insurance agents with the size, placement, square footage and building materials of our ancestors’ properties. First drawn in 1867, Sanborn maps are notable for their detail and use of symbols, often with color-coding to indicate building material (stone, adobe, brick, etc.). That level of detail provides interesting information about our ancestors’ homes and workplaces.

In addition, the Sanborn Map Co. consistently made these maps over the years, making them one of the more reliable collections of maps. With these maps, you can watch your ancestors’ living and working environments transform across generations. Use them in conjunction with census records and city directories to bring your ancestor’s neighborhood to life.

The Library of Congress has an extensive collection of digitized Sanborn maps. Simply search for your ancestor’s hometown, then click a map collection to view it in detail. Results may contain multiple sheets, so you may have to flip through pages to find a particular area of town. Local public and university libraries may also offer digitized or printed maps for the surrounding region. For example, your library may subscribe to a Sanborn map database available through ProQuest.

This map from the Library of Congress’ collection depicts West Chester, Pa., in 1886. According to the collection’s key (on the first sheet of this county’s maps), yellow buildings are “frame,” while red signifies brick and blue indicates stone. One building may actually be made up of different materials. The map even labels individual buildings (“Horticultural Hall”), as well as what buildings hold (“Coal Shed,” “Lumber Shed,” etc).

A version of this article originally appeared in the July/August 2016 issue of Family Tree Magazine.