Disappearing Bridges
Photographic catalog by Daniel Alward of historic iron and steel bridges mainly in Pennsylvania.
http://www.venangoil.com/Bridges.html
Old Covered Bridges of Pennsylvania
Photographs and information from Dr Roger McCain.
http://william-king.www.drexel.edu/top/bridge/CB1.html
The Theodore Burr Covered Bridge Society of Pennsylvania
Promotes the preservation of covered bridges in the state. Includes details of activities, an illustrated guide to truss types and a list of covered bridges in the state.
http://www.tbcbspa.com/
