Parks Bar Bridge, Spanning Yuba River at State Highway 20, Smartville, Yuba County, CA

Significance: The Parks Bar Bridge is significant under Criterion C, as a distinctive example of an unusual method of construction. It is one of the earliest and largest remaining examples of the Thomas System of pre-cast, reinforced concrete, three-hinged arch bridges. This early 20th-century design and method of bridge construction was patented by William M. Thomas during his association with W.S. Post in their Los Angeles engineering firm of Thomas and Post. This is the sixth of approximately seventeen Thomas System bridges built in California, and one of only three remaining. The bridge was determined eligible for the National Register of Historic Places in 1986.
Survey number: HAER CA-132
Building/structure dates: 1913 Initial Construction
Building/structure dates: 1924 Subsequent Work