Sanborn Fire Insurance Company maps
These large, detailed maps were made for every burg in America between the late 1800s and the mid-1900s. They were printed in large (maybe 2 by 3 feet) books, and may be available on microfilm or online.
Intended for the calculation of fire risk, these maps show the exact placement of every structure on every lot, including houses, factories, sheds, outhouses, garages, stables, stores, mills, etc. They include information on the town's population, water supply, street lighting, and fire department. The materials used in each building are indicated, which can help you sort out the various renovations or establish the house's former appearance. Fire hydrants and water mains are sketched in. Width of streets and alleys is indicated. More facts are given for commercial buildings, including the type of business conducted there, the type of lighting and heating used, the number and placement of windows, the fire hoses and buckets provided, and even whether there is a night watchman.
The precise years when the maps were updated for a given city are totally random, and they tend not to show sparsely settled areas of town, so although my house was present when my town's first Sanborn map was drawn, our block wasn't shown.
Sanborn maps can help you:
Narrow the time frame when the house was built
Retrace the various renovations (my house's owners added a wrap-around porch between the 1890 map and the 1902 edition)
Establish the age of current garages and other secondary structures
Reconstruct the past appearance of the whole property. I saw an octagonal gazebo in our neighbor's yard, and my husband found two old privies.
Then there's always dumb luck: A nearby house was noted as being under construction at the time the map was drawn, establishing the EXACT build date.
Where to look for Sanborn maps:
University and state libraries
Historic preservation nonprofits
Local historical society/museum
Library of Congress
Last edited by melissakd
on Sat Apr 14, 2012 7:37 pm, edited 2 times in total.
The Thaddeus W. Bayless House
Built between July 1863 and January 1865, major add/reno between 1890 and 1902
Style = Mutt