Before SEPTA, public transportation in the city was largely the responsibility of the Philadelphia Transportation Company (PTC) and its predecessor, the Philadelphia Rapid Transit Company (PRT).  HSP's Harold E. Cox Transportation collection (#3158) is an invaluable resource that documents the history of these organizations and of public transportation generally in Philadelphia from the mid 1800s to the mid 1900s.  Thanks to the wonderful team from the PACSCL Hidden Collections Processing Project, this collection, with boxes and volumes that number into the hundreds, has been processed!  Processors Celia Caust-Ellenbogen and Michael Gubicza have written about their experience with this collection and provided pictures over on the PACSCL blog.  Click the link to find out more!