Monday, June 11, 2007

Using Sanborn Maps to Find History of Your House

Researching the history of your house can be a jigsaw puzzle or a scavenger hunt. But like a a good detective knows his sources, a house historian knows the likely places to find a lead. Sanborn Insurance Maps are one of those sources. Created by the Sanborn Fire Insurance Company in the late nineteenth to early twentieth centuries, these incredibly detailed maps lead the way to historic treasures.

The Sanborn Fire Insurance Company created these maps to help evaluate fire risk and existing construction. Not every aspect of a house or building was be recorded (for example, the company did not care what color the house was painted), but what was included is tremendously useful. You can expect to find:

* the footprint or shape of the building
* use (house, apartment, store, restaurant, factory)
* the street name and address (especially useful if lots have been renumbered)
* how many stories it had
* location, number, size, and shape of porches
* the basic construction material (frame, concrete block, tile, etc.)
* setback from the street
* width of the street
* location of water tanks, wells, cisterns, or fire hydrants
* additions
* nearby buildings
* nearby public utilities (water mains, train tracks, streetcar lines)

Since the company wanted to keep current records on the structures they were insuring, the maps were meticuously updated every few years. These updates help narrow timeframes for when a building might have been built, or when a room was added, information that is very useful for determining what is original, historic, or modern in a particular house.

Sanborn maps were created for cities all over the United States, including Florida. These maps, however, focus on the properties within city limits or particular factories. Your particular house may not be included, or may only be on maps from certain years. Although Sanborn maps are valuable resources in urban areas, rural houses are rarely found. Another possible problem comes from how these maps were updated. The Sanborn company created these maps for their own business use, not as a future archive of historic structures. The maps themselves are in large atlases, and when they were updated, snips of paper were glued on top of the old map, obscuring the drawings below.

Original Sanborn maps can be found in local public and university libraries, as well as in some governmental offices. However, due to the size, age, and importance of these documents, access may be limited. For these same reasons, as well as copyright issues, photocopies of the originals are usually prohibited.

But don't despair. Those same public and university libraries and historical societies often have microfilm copies of the maps, which although they are in black and white, have most of the same information and you can print copies. Some libraries provide online access to their cardholders, and the University of Florida has color images of many Florida Sanborn maps available to anyone on line.

Sanborn maps are an important piece of the puzzle for finding your house's history.


  1. Anonymous8:18 AM

    Sanborn maps are also a great resource to see the former names of streets and former layouts (though not complete or completely accurate) and railroad layouts. Too bad the Tampa Sanborn maps only go up to 1922, since Tampa really didn't get jumping until the mid 20s!

  2. I agree it's frustrating that there aren't more maps. It's not quite as bad as it seems -- the 1931 and 1931/1951 Sanborn maps in black and white are available as microfilm in Tampa area libraries, and online through the Tampa-Hillsborough County Public Library. Go to their website, to the Information Gateway section, History, then Digital Sanborn. (A Tampa library card barcode is needed.)

  3. I really enjoyed looking at these old maps thanks for the link.

  4. Anonymous2:22 PM

    The maps are also available through the University of Florida Digital Collections, and handy browse views by thumbnail and by year:

    They even have a project called Ephemeral Cities using the maps with lists of features, like this:


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