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Using The Sanborn Fire Insurance Maps

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USING THE SANBORN FIRE INSURANCE MAP

We’ve done a blog post in the past concerning our Sanborn Fire Map collection, and I wanted to go one step further; while the previous post dealt with the nature and scope of the collection, I wanted to show you how to use the maps for your property research.  We have digitized maps from 1886, 1894, 1909, and 1909-1949 for Covington and vicinity, and a subscription for the entire state of Kentucky in the years that are digitally available; print maps of Covington (Vol 1) and the surrounding areas (Vol  2) that originated 1909 and are physically updated through about 1950; and 1946-1992 on microfilm.

I begin below with an annotated graphical introduction to the characteristics of the maps and a view of the Sanborn’s key map.  Whether in print, digitized, or on microfilm, each ‘map’ is a set of multiple pages of enlarged maps preceded by a key map and symbol key.  Each year has slightly different symbols and color codes, so be sure to check the key for the year that you are using.

Since the Sanborn maps are of more densely settled areas, I’ve also included a view from a county atlas in our collection so that you can see the types of information included in these resources in comparison to the Sanborn maps.

Lastly, I’ve included a view of the enlarged map of a property in Covington in 1886; on this map I’ve noted the characteristics that can be either directly observed or interpreted through the use of the key.

 USING THE SANBORN FIRE INSURANCE MAPS TO LEARN ABOUT YOUR HISTORIC PROPERTY

One of the most important things to know when trying to read any map is the purpose and conditions for which it was created.  This applies to the Sanborn maps as well, which were created by the Sanborn Map Company.  They were intended to help property insurance companies determine their liability and exposure in the case of fire and therefore: they focus on urban areas; they were updated frequently; and they include characteristics of the built environment that influence flame sources, flame spread, fire suppression, and egress; and.  I’d like to look at each of these categories of information that the Sanborn maps provide and how the information that’s made accessible can help you understand the evolution of your historic building.

A FOCUS ON URBAN AREAS

  • The Sanborn maps focus on urban areas where fire can spread easily between buildings and where flame sources were plentiful. While fires occurred in rural areas and could destroy all of the farm’s outbuildings, these areas didn’t have a sufficient density of insurance subscribers to make mapping rural areas a viable interest to the industry; as such, if you are researching a property in a more rural area, county or state atlases are your best bet.

FIRE PROTECTION CHARACTERISTICS

  • An insurance company would need to know whether the house they were about to insure was built of flammable materials, if it was located near a structure where a fire might more easily start, such as a foundry, and the proximity of fire hydrants and engine companies for fire suppression.

They highlight fire and safety characteristics of the structure such as:      that impact:

  • Layout and sizing of fire hydrants and supply lines                             flame suppression
  • Construction materials of exterior walls and roofing                          flame spread
  • Chimney construction method and materials                                       flame source
  • Window and skylight arrangements                                                       egress and flame spread
  • Means of heating and lighting of industrial buildings                        flame source
  • Structure function (e.g. dwelling versus foundry)                               flame source
  • Relationship between buildings                                                              flame source and spread
  • Some details of interior arrangements (interior masonry fire walls, space usage when it influences fire source/spread or egress, etc.)

ANATOMY OF A SANBORN ENTRY

I hope that this post has helped you to understand the vast scope of information that can often be mined from maps.  As always, feel free to contact us or stop in with any questions or if you’d like help using maps for your research.  If you are interested in learning more, also check out Insurance maps: their history and applications by Diane L. Oswald, which provides an overview of the creation and use of Sanborn Fire Insurance Maps.

This blog was written by Erica Stepler-Cavin, MLIS, Local History and Genealogy Library Associate at the Kenton County Public Library – Covington.

 

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