The Library of Congress has an extensive collection of digital images of Sanborn fire insurance maps for the United States.
http://www.loc.gov/rr/geogmap/sanborn/?loclr=twmap

The Library of Congress has an extensive collection of digital images of Sanborn fire insurance maps for the United States.
http://www.loc.gov/rr/geogmap/sanborn/?loclr=twmap
Thank you so much for this link!