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Mill Rock Bridge


Downstream Elevation Showing Relationship Of Bridge To Surrounding Farms, Looking Sw

Photo by J. Ceronie, photographer, Bennett, Muessig & Associates, Ltd., Iowa City, IA, February 1983, for HAER

View photos at Library of Congress

BH Photo #123358



Lost Pratt through truss bridge over Big Bear Creek on 33rd Avenue in Monmouth Township
Monmouth Township, Jackson County, Iowa
Replaced by new bridge
Built 1913; Replaced 1995
- Clinton Bridge & Iron Works of Clinton, Iowa
Single span, six-panel summetrical Pratt through truss structure, with steel superstructure, riveted connections, concrete deck and concrete abutments.

"The Mill Rock Bridge was erected by Clinton Bridge & Iron Works, a major Iowa bridge contractor. It is locally significant as an early instance of the use of riveted connections and concrete deck in county bridge construction. These were among features which were to become standard in subsequent decades due to the establishment of the Iowa State Highway Commission and the Commission's enforcement of design standards for various kinds of crossings. Because the Mill Rock Bridge does not display all features associated with this standardization program, it may be considered an illustration of the transition from county to state control of local bridge design and construction.

"The Mill Rock Bridge was documented bu Bennett, Muessig & Associates, Ltd., Town City, Iowa, for the Board of Supervisors and County Engineer, Jackson County, Iowa, in 1983. The project team comprised of J. Ceronie, photographer; Matha B. Bowers, historian; and Bruce A. Hatms, photographic assistant."

Span length: 101.0 ft.
Total length: 101.0 ft.
Deck width: 14.6 ft.
Approximate latitude, longitude
+42.05556, -90.86111   (decimal degrees)
42°03'20" N, 90°51'40" W   (degrees°minutes'seconds")
Approximate UTM coordinates
15/676987/4658157 (zone/easting/northing)
Quadrangle map:
Inventory number
BH 37389 (Bridgehunter.com ID)

Update Log 

  • September 9, 2008: Added by J.R. Manning


  • J.R. Manning - thekitchenguy [at] sbcglobal [dot] net
  • HAER IA-7 - Mill Rock Bridge