https://www.philageohistory.org/geohistory/

GPGN contains maps, atlases, city directories, site surveys, and more dating from the 17th century through the present day. Users may search geographically-organized information and materials that display the development of greater Philadelphia. Its goal is not only to create a resource for maps of Philadelphia, but also to give the public resources for understanding historic Philadelphia. GPGN also offers an educational resources section that can be used by teachers of grades 3-12. The project is sponsored by the Philadelphia Area Consortium of Special Collections Libraries (PACSCL) with assistance from the Athenaeum of Philadelphia and its partners.