The Emlenton Bridge is a steel-deck truss bridge that spans the Allegheny River just south of the town of Emlenton, Pennsylvania, United States at approximately mile marker 44.4 on I-80. With a height of 270 feet (82 m) above the river, the Emlenton Bridge was the highest bridge in the Interstate Highway System when completed in 1968 (The Lewiston-Queenston Bridge is higher but is technically an international bridge, not part of the Interstate Highway system). This record was held until 1971 with the opening of the Fred G. Redmon Bridge near Selah, Washington.
The Emlenton Bridge remains the highest road bridge in Pennsylvania; with an overall span of 1,668 feet (508 m) it was the largest bridge constructed as part of the Keystone Shortway project. With the completion of the Interstate System, it is likely that the Emlenton Bridge will remain the fifth-highest bridge in the system for a significant time, behind the Glade Creek Bridge in West Virginia, the Pine Valley Creek Bridge in California, the Galena Creek Bridge in Nevada, and the aforementioned Redmon Bridge.
An interesting fact about the Emlenton Bridge is that due to its size, and geography of the land, it is actually located in three different Pennsylvania counties. One side of the bridge is in Venango County, the other in Clarion County, but the southwest abutment resides in Butler County.