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The State Library of Iowa has online access to the Sanborn Fire Insurance Maps for cities throughout the state, including Des Moines. The Sanborn Fire Insurance Maps were created to assist insurance agencies in determining insurance risk for individual buildings. The originals consist of bound books, indexed by street address range, that map out property lines, building footprints, and construction type.

Historically, insurance companies relied on these books to underwrite policies. Today, precise actuarial tables take into account a broader variety of structural and owner characteristics, and the Sanborn maps are used primarily in historical research - they remain one of the most complete accountings of the urban built environment available.

Through the State Library of Iowa, the Sanborn maps from 1884, 1891, 1901, 1906, and 1920 (with updates into the '50s) are available online. The earlier maps, up to 1906, only cover a small portion of the current Des Moines city.

In order to access the maps online, you must register for a FREE State Library of Iowa card number. The administrator will e-mail you your assigned access number within a few days.

Once you have your library card number, use it to log in to http://www.statelibraryofiowa.org/services/resources/sanborn-login. Simply follow the instructions for accessing the maps for the town you are interested in. You will probably have to zoom in on the first few pages (which are the index) to find the address you are looking for.

Other State Library of Iowa online research resources are available at http://www.statelibraryofiowa.org/services/resources.

Though they stopped updating the fire insurance map books in 1970, the Sanborn company still exists.