The LA Public Libary has an oline collection of Sanborn Maps reports Glen Creason, Map Librarian -- History & Genealogy Department:

An excellent starting place for cartographic insight is the digital collections of Sanborn Fire Insurance atlases hiding in plain sight on the Los Angeles Public Library's website within the library's databases. The Sanborns used to be just the domain of architectural historians, baseball researchers or folks slated to stand before city planning boards when they wanted to improve their property. 

http://www.huffingtonpost.com/the-los-angeles-public-library/sanborn-fire-insurance-atlases_b_1656648.html