books.google.com - Includes detailed maps of the known routes and railroad sites. Organized in antebellum America to help slaves escape to freedom, the Underground Railroad was cloaked in secrecy and operated at great peril to everyone involved. The system was extremely active in Pennsylvania, with routes in all parts...http://books.google.com/books/about/The_Underground_Railroad_in_Pennsylvania.html?id=WPFYoBL6bGsC&utm_source=gb-gplus-shareThe Underground Railroad in Pennsylvania
