San Francisco Public Library provides access to the Sanborn Fire Insurance Maps for California.
Remote access is provided through the Articles and Databases link under eLibrary.
Sanborn Fire Insurance Maps for San Francisco span 1887-1950.
New article on Sanborn Fire Insurance Maps! Tanvi Misra discusses how Sanborn Maps show the evolution of cities in the article The Accidental Revelation of Sanborn Maps. Read the article on the Atlantic's CItyLab blog.
Digital Sanborn Maps Key