Philadelphia City Archive
PhillyHistory.org, the website of the Philadelphia City Archive, gives the following descriptive information:
The Philadelphia City Archive is one of the country's largest municipal archives, with about 2 million photographs, dating from the late 1800's. Discover gorgeous images of Philadelphia, its industry, architecture, culture, and people.
All archive photos may be searched by keyword and date. Archive photos which have been assigned a geographic location are also searchable by proximity to an Address, Intersection, Place Name, or Neighborhood.