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Sanborn Maps

Insurance is and always has been a tricky business. Modern companies, outfitted with technology that would have astounded people of the past, remotely assess and insure communities across the country. Each data point contributes to the final calculation, determining levels of risk and ultimately premium prices. Strides forward in technology, such as satellite images and massive databases provide all the information necessary to perform such calculations, yet are just more complex versions of the two dimensional maps used in the early days of the profession.

Historically, insurance was largely issued by local merchants who could visit and assess individual residences. The benefit to this model was the ability to monitor and accurately assess the areas coverage; however, in 1835 fires in New York caused damage that exceeded the compensation local vendors could provide and with little reserve funds, many went out of business. Legislation and regulations requiring sufficient reserve accounts was passed and the small vendor was no more. Larger corporations swept in to provide insurance services, but lacked the ability to visit each location. One solution to this problem was to pack as much data as possible into maps that could be viewed by adjusters in state and regional facilities for use in their calculations. The amount of detail included in each work is phenomenal and one man managed to make a name for himself in the industry that still survives today.

Sanborn Maps: A Brief History

The namesake of the Sanborn Fire Insurance Map Company can be traced to its founder Daniel Alfred Sanborn. Born April 5, 1827 in Somerville, Massachusetts, Daniel would grow to become a surveyor and eventually create maps in America beginning in 1866, when he was employed by the Aetna Insurance Company to prepare maps of several cities in Tennessee. Sanborn would then go on to produce an insurance map of Boston in 1867, which would be the first of many detailed maps ascribed to his namesake.

Sanborn’s early success with insurance maps was most likely a motivating factor for him to start his own company and in 1867 he established the D. A. Sanborn National Insurance Diagram Bureau in New York City. A publishing plant was opened in Pelham, NY and the mapping empire grew. The firm name was changed in 1876 when it was incorporated under the name Sanborn Map and Publishing Company, which then became the Sanborn Perris Map Company, Ltd., until, in 1902, the name was shortened to the Sanborn Map Company, the same name which the company still uses today. Despite Sanborn’s death in 1883, his name and legacy lived on.

The mapping empire produced numerous works for cities and towns in the United States, but also in other countries, such as Canada and Mexico. Published throughout the nineteenth and twentieth centuries, approximately twelve thousand maps were produced, with individual sheets extending into the hundreds of thousands. The last map series was published to microfilm in 1977, ending more than one hundred years of mapping America. The company still survives today providing geospatial mapping services and continues the legacy set by its founder.

About the Maps

Each Sanborn map is a colorful work of art packed with a wealth of information. Individual sheets measure 21 inches by 25 inches and are bound into a large volumes holding all sheets for each respective town. It was not uncommon for smaller municipalities to be confined to a single sheet of paper. With a scale of 50ft to 1 inch (1:600) commercial, industrial, and residential sections of town were rendered in high detail. Initially the maps were not for public use, but rather made exclusively for insurance companies.

Individual surveyors were not credited on the maps; however, their personal artistic taste can be seen on the often ornate tittle pages of some volumes. An index on the title page illustrated the total area depicted in the volume, with individual sections covering a few city blocks designated by number to link them to the page where that corresponding area was fully rendered. The index also listed prominent businesses and organizations on the map. The title page also featured the key, one of the most important parts of the map, identifying the various symbols and colors used. Yellow buildings were wood framed and blue structures were made of brick, stone, or concrete. With more than fifty symbols in the key, each structure was portrayed at an incredible level of detail, but there was more. Notes on individual pages portrayed what type of heating method the structure used. If the building was a factory, the map often outlined the specific process performed on each floor. Most importantly for insurance purposes it was noted if there was a night watchman for the facility, whether or not the grounds were lit at night, or if it contained a hose in case there was a fire. The maps were even updated between printings. Agents would be equipped with additions that would be adhered to the master map. The Sanborn Maps had it all, or did they?

Although the maps contained a wealth of information, what they did not contain does speak to the biases of the time. Poorer sections of town or those who could not afford insurance were often excluded from the map, which often left significant pockets in city data. It also was not uncommon for surveys to exclude certain groups based on race, class, or religion. Despite its shortfalls, the Sanborn Maps serve as an excellent snapshot of the nineteenth and twentieth century American landscape.

The Sanborn Maps of Indiana County

Initially, in Indiana Borough, the Sanborn Maps covered a rather small swath of land in the downtown area radiating from the intersection of Philadelphia Street and Sixth Street, where the old courthouse now stands. Many of the buildings have small footprints and were constructed largely of wood. As the town grew, so did the coverage area on the map. The intersection of Wayne and Sixth where the Historical Society now stands was the very edge of one of the sections on the map until 1903 when the service area expanded and included coverage to the southern limits of Memorial Park. The change in the size of buildings and materials used to make them further emphasize the prosperity of nineteenth century Indiana.

The location of the Historical Society in January 1910

When agents from the Sanborn Map Company came to survey Indiana, their arrival was big news and was often mentioned multiple times in the local newspapers. It was also noted that some of the sons of Indiana worked for the Sanborn Company and were off in the world producing maps. Indiana Borough was not the only location in the county that warranted a map, with volumes also being produced for Glenn Campbell, Blairsville, Cherry Tree, Homer City, and Black Lick.

Modern Use of the Maps

Today the Sanborn Maps have fallen out of use by insurance companies. Fortunately, they are incredibly useful to other fields of study. The maps serve as an excellent resource to date a home or verify the existence of a business. Additions to structures and the division of property can also be closely tracked. As mentioned before though, there can be pockets in the data. On occasion, even the most affluent areas towns are excluded. This is the case with the Society’s own Clark House. Although constructed in 1869, the house does not appear on the Sanborn Maps for a period of almost thirty years even though its general location was home to some of the largest dwellings in Indiana. The names of roads and the formation of side streets and alleys can also be tracked. Because the maps are constantly updated, the viewer gets an excellent perspective on the growth occurring in the town in unique snapshots.

The main purpose of the maps may have faded from use, but they have been reborn as a great resource for genealogists and historians. The amount of detail found in these documents is a valuable asset and an excellent tool. Although the maps may have shortcomings, they provide a fine snapshot of the nineteenth and twentieth century American landscape. The Sanborn Fire Insurance Maps, another excellent resource located in the Helman Library.


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