Exploring history with Sanborn Maps

If you are researching a historic house or structure, the Sanborn Map is a great resource. Sanborn Maps documented the infrastructure of urban areas in Indiana starting in 1883. Although no regular schedule was followed, each city map was updated every 5 to 15 years.

Each map documents the structures at the date of publication, coded by color and symbols to identify elements of the building. For each structures, you can learn the building material, number of heights, and window openings. A great history of the Sanborn Maps is available at the Library of Congress (http://www.loc.gov/rr/geogmap/sanborn/san4a1.html). Using the Sanborn Map can uncover many secrets about your building’s history – so how do you use them?

Well, first of all, where can you find Sanborn Maps in Indiana? Originally, Sanborn Maps were printed and bound in large, hardcover books each time new maps were published. Some libraries and archives house these books, but you will find more coverage and ease of access through microfilm copies or online databases. The Indiana State Library (http://www.in.gov/library/) houses all the Sanborn Maps for Indiana on microfilm. Recently, the Indiana University Spatial Data Portal added digital, scanned, color copies of Indiana Sanborn Maps on their website http://gis.iu.edu/datasetInfo/sanborn.php. Other libraries and archives may have access to select cities or areas.

Let’s make it simple. What Sanborn Maps are available for Decatur County? Here are the offerings:
Greensburg: 1883, 1887, 1892, 1899, 1906, 1913, 1927, 1947

Milford: 1893, 1897, 1905, 1910, 1917

St. Paul: 1927

 

Figure 1

So, once you’ve found your map, what next? An individual city’s map for each year will include a small “mini” map with a key identifying how the map was divided geographically. This key (Figure 1) is the guide map from the 1887 Greensburg Sanborn Map. Now, let’s say we’re researching the Decatur County Courthouse. From the guide map, we discover the structure is on page 2 (Figure 2). Some early maps or smaller cities may not include a guide map if the city’s coverage is limited to one or two pages. The page numbers for each map are located in the upper right hand corner.

Figure 2

Using a Sanborn Map Key (http://www.in.gov/library/images/mapkey.jpg), you can gain some great knowledge about the building at the date the map was published. Let’s use the 1887 Greensburg Map, sheet 2, with the Decatur County Courthouse as our example. The pink color with circles tells us the courthouse is a brick building. The ‘2’ tells us the structure is two stories tall. The tick marks along the outer edges of the building indicate the number of window openings. Other details tell us the courthouse has two towers, the interior space included offices, and the structure has a hip roof.

Now, let’s compare the 1887 map to the 1913 map of the Decatur County Courthouse (Figure 3). The updated map shows the structure maintains the same basic shape with two stories of brick. This map gives a basic floor print of the interior and indicates the courtroom space. Overall, both maps indicate the building has not changed significantly from 1887 until today. 

Figure 3

Things to keep in mind when using Sanborn Maps: address numbers and street names may have changed from the publication of certain maps. Sanborn Maps may tell you what kind of use the structure had at the date of publication. Lastly, Sanborn Maps typically focused on the “center” or downtown area of a city. If your historic building is on the edge of a city, it may or may not be included. In some cases, major institutions or companies that had facilities outside of the town would be included as a smaller map within a single sheet. Using a contemporary map (Google Maps, for example) as a reference will help you visually determine whether or not you’ve found the correct structure on the Sanborn Map.

With these basic tools, you can explore Sanborn Maps in your own community. Sanborn Maps will provide some great information to date your structure, determine the overall form, and might mention the owner or use of the structure at that time. 

Sanborn Maps used in this article found in the Indiana Spatial Data Portal.

Post written by Raina Regan.
Raina is an architectural historian employed by the Indiana National Guard. Her work encompasses statewide cultural resources projects with National Register eligible or listed structures. Raina has a Bachelor of Arts in Art History and Visual Culture from Michigan State University and a Master of Science in Historic Preservation from Ball State University.