Gillespie Dam Bridge

Gillespie Dam Bridge Interpretive Plaza Sign


Gillespie Dam Bridge spans the Gila River on Old US Hwy 80 between the communities of Arlington, AZ and Gila Bend, AZ and is a unique and elegant reminder of Arizona's rich past and America's transportation history. Gillespie Dam Bridge construction efforts started in February 1926 and was opened for traffic on August 1, 1927. The [bridge] is historically significant as one of the most important examples of early bridge construction in Arizona. On May 5, 1981, the property encompassing the bridge and dam was placed on the National Register of Historic Places by the United States Department of the Interior. During the winter of 2011, the bridge underwent a $7.3 million rehabilitation effort by the Maricopa County Department of Transportation. In 2012, the project was designated an Arizona Centennial Legacy Project which included the construction of the interpretive plaza.





Gillespie Dam Bridge facing west-southwest.




The Historic Ocean-to-Ocean Highway and Gillespie Dam Bridge


In 1909, Arizona's Territorial Legislature created the Office of the Territorial Engineer to develop a system of roads connecting Arizona's major cities and towns to improve delivery of the US Mail. Shortly after Arizona statehood in 1912, the state engineer surveyed a major east to west transportation route across southern Arizona between the towns of Clifton and Yuma. This early highway route followed the Gila River west from Phoenix, turning south near the small town of Arlington. A bridge crossing was constructed further upstream at Antelope Hill, however, this highway route proved to be unreliable due to frequent washouts during heavy rains and flooding.

In 1921, the highway route was realigned to pass over the Gila River just below the newly constructed Gillespie Dam. The new route was known as the Phoenix-Yuma Highway. The following year, a concrete apron was built downstream of Gillespie Dam to help automobiles cross the Gila River. This crossing point also proved to be unreliable, as high water often made passage difficult.

On August 1, 1927, Gillespie Dam Bridge opened to traffic and was officially designated part of the early Southern Transcontinental US 80 Highway.

Lee Moor built the nine-span steel truss bridge for a cost of $320,000 ($4,255,760 yr.2012 equiv). The 1,662 foot long bridge was unique for it's time being one of the longest bridges and largest steel structure in the state. Bridge design elements include a connected series of rigid trusses weighing 2.3 million pounds. The bridge has a total of nine steel truss spans. Each steel truss features a camelback web configuration with a built-up box beam for the upper and lower steel members. The trusses are supported by solid concrete abutments and pier columns placed on bedrock at a depth of 25', with the deepest pier extending 43' below the riverbed.

The new bridge and US HWY 80 through the Arlington Valley became part of the national "Ocean-to-Ocean Highway". In 1956, the interstate route was decommissioned, then operation, care and ownership of the bridge were transferred from the State of Arizona to Maricopa County.

Source: 'Historic Gillespie Dam Bridge' sign seen in picture above. Click to enlarge.

Original 1927 Gillespie Dam Bridge Roller Bearing


Original Gillespie Dam Bridge Roller Bearing 

As Gillespie Dam Bridge approached it's 85th year of service, the Maricopa County DOT began a major rehabilitation and repair effort to save this gem. Rehabilitation activities included: Head straightening of bent steel members damaged over the years by automobiles and large farm vehicles; Pipe rail and sway bracing repairs; Installation of new approach guard railing; Concrete repairs and wing wall modifications; and reinforcement of bridge piers.

A significant aspect of the rehabilitation project was the span-by-span hydraulic jacking of the bridge to remove the original rusted, non-functioning roller bearings. New modern pad bearings were installed as part of this effort which allow for the necessary expansion and contraction of the steel spans during changes in temperatures.


Source: 'Original 1927 Bridge Roller Bearing' sign seen above. Click pictures to enlarge.

Where There Is Water, There Is Life


The Gila River and irrigation canals feed the Arlington Valley for prime agricultural development and diverse wildlife ecosystems. Riparian zones off the Gila River provide a lush environment for many types of birds and mammals to thrive in while the journey through developed farm lands leading to Gillespie Dam Bridge provide some of the best Raptor viewing in the state during and around the cooler months. Hawks, falcons, kites, eagles and many more birds migrate to the area making the Arlington Valley a sweet spot close to the metro valley for birding. The area is maintained well by the locals and county and all who choose to visit are urged to respect the surrounding environment.

For some wildlife and landscape photos of my time in Arlington Valley, feel free to visit here.

Source: My experience. Click left picture to enlarge.




Gillespie Dam Bridge Side View

Gillespie Dam Bridge sideview.



Gillespie Dam

Gillespie Dam.





Text sources on this site have been briefly summarized from the informational structures placed on and around the interpretive plaza. This page is intended for educational purposes and all photos are copyrighted with restricted use by the author. Feel free to download or link to any photos for non-commercial use only.

©2012 Bryan Slavinsky