The Rockville Bridge is the longest stone masonry arch railroad viaduct ever built, at 3,820 feet (1,160 m). It has 48 70-foot spans.

The bridge crosses the Susquehanna River about 5 miles (8 km) north of Harrisburg, Pennsylvania. The eastern end is located in Rockville and the western end is just south of Marysville.

Completed in 1902 by the Pennsylvania Railroad (PRR), it remains in use today by the Norfolk Southern Railway and Amtrak's Pennsylvanian route.

The bridge was listed on the National Register of Historic Places in 1975 and was designated as a National Historic Civil Engineering Landmark in 1979.

The first bridge erected at this site was a one-track wooden truss built by the PRR and opened on September 1, 1849. The Northern Central Railway began to use it after abandoning its Marysville Bridge.

It was replaced in 1877 with a double-track iron truss bridge.

The third and current bridge was built between April 1900 and March 1902 by Drake & Stratton Co., which erected the eastern half, and H.S. Kerbaugh, working from the west. The laborers included men of Italian heritage and local residents.

Control of the bridge passed to Penn Central after the PRR merger in 1968, then to Conrail and finally the Norfolk Southern.

For most of its life, the bridge carried four main line tracks, which were reduced to three during the 1980s when the former PRR Main Line was modernized across Pennsylvania.

In the late 1990s, an intermodal container was blown off an intermodal freight train and landed in the river, prompting Norfolk Southern to stop using the wye track to Enola at the west end of the bridge. This reduced the number of main line tracks to two, but left a buffer zone on either side to prevent further containers ending up in the river, although high winds from the departing December 2010 North American blizzard sent another overboard on December 27, 2010.

The track from the west side of the bridge was shortened to a new control point named "Mary" because the curve in the switch at the former location caused lateral forces to blow out the side of the spandrel. This led to the failure of the downriver side under the weight of a coal train. When the spandrel failed, it also disproved the once-popular thought that the core of the bridge was filled with concrete.

During times of high wind, it is routine to park heavy trains on the bridge as a wind shield.

Currently, the bridge is used by the Norfolk Southern Railway and Amtrak.

• List of bridges documented by the Historic American Engineering Record in Pennsylvania
• List of crossings of the Susquehanna River

• 
  Looking west from Susquehanna Township
• 
  Two Norfolk Southern freight trains meet on the Rockville Bridge

• Cupper, Dan (2002). Rockville Bridge -- Rails Across the Susquehenna. Withers Publishing, Pennsylvania (USA). ISBN 1-881411-34-6.
• Jackson, Donald C. (1984). Great American Bridges and Dams. John Wiley & Sons, New York (USA). ISBN 0-471-14385-5.
• Spavins, Jim (2009). 90 Days to Rockville. CreateSpace, California (USA). ISBN 978-1-4486-5534-2.

• Historic American Engineering Record (HAER) No. PA-524, "Pennsylvania Railroad, Rockville Bridge"
• Pennsylvania's Historical Architecture and Archaeology site photos: [1] [2]
• Rockville Bridge (photos and information)
• Rockville Arch Bridge at Structurae
• Rockville Bridge Photos (November 5, 2005)
• Stan's Railpix : Conrail Photo Gallery ( Rockville Bridge photos from Nov -1994 )