Sanborn Fire Insurance Maps
http://www.loc.gov/rr/geogmap/sanborn

A searchable database of the 50,000+ fire insurance maps published by the Sanborn Map Company housed in the collections of the Library of Congress Geography and Map Division. Includes links to 6,000+ digital images in the Library of Congress collection. This nhas been added to the tools section of Research Resources Subject Tracer™ Information Blog.