Sanborn maps were originally used as a way for insurance underwriters to track houses under their domain, but today, they've become a valuable research tool for those hunting for historical data on old houses.
You can still page through the fragile, hand-colored original maps at local or university libraries, but many have also put their Sanborn maps online for easier access—and some have even taken advantage of new digital technology to enhance the Sanborn research experience. We've highlighted some of the best collections below:
Yale University Map Collection: In addition to its full print collection of Connecticut's Sanborn maps, Yale has also merged its maps of New Haven with Google Earth to allow users to view current satellite photos of the town side by side with Sanborns from the late 19th and early 20th centuries.
Digital Library of Georgia: The University of Georgia's Sanborn collection boasts more than 4,000 maps of cities and towns in Georgia, and allows you to search by address.
University of Nevada-Reno: This collection merges Sanborn maps with historic photos of Nevada buildings to give browsers a complete picture of the state's rapidly changing built environment.
University of North Carolina's Docsouth: This project, entitled "Going to the Show," uses Sanborn maps of North Carolina towns to trace the experience of movie-going in film's early days. But it's just as illuminating for homeowners in the 44 towns featured in the project, who can view Sanborn maps of their locations overlaid on current Google satellite images.
ProQuest Digital Sanborn Collection: The digital arm of the Library of Congress's Sanborn map collection, ProQuest boasts 660,000 digital maps, which you can call up by state, city, and year. The only catch? Subscription to the service is available to libraries only, so you'll need to check with your local branch to see if they have access.
UC-Berkeley Library: This comprehensive list of available Sanborn maps is organized by state, with asterisks to denote states that maintain online collections.
Library of Congress: Here, you'll find plenty of background information on Sanborns (including detailed descriptions of map markings and case studies on their importance for historical research), plus a full list of links to local libraries with Sanborn collections.
University of Virginia Geostat Center: If you need help deciphering a Sanborn map key, this site provides an easy-to-understand, picture-filled guide.