The Plattsmouth Bridge carries U.S. Highway 34 over the Missouri River between Mills County, Iowa, and Cass County, Nebraska. Located immediately downriver from engineer George Morison's 1880 railroad bridge, the immense structure consists of seven spans: a 402-foot cantilevered through truss over the river's navigable channel, anchored by 201-foot through spans, with two 203-foot and two 104-foot deck trusses on the eastern flood plain. The bridge was constructed in 1929 as a toll structure for the Plattsmouth Bridge Company, a privately held corporation. (The bridge is still operated for tolls by the company.) The bridge was designed, fabricated and erected by the Omaha Structural Steel Works, with a total construction cost reported as $639,361. With its sharp angularity and somewhat graceless profile, the Plattsmouth Bridge resembles some of the 19th century pin-connected trusses over the Missouri River. But its riveted connections and modestly Moderne channel piers indicate the relatively late construction date. The bridge's 20-foot roadway width places it among the narrowest of the extant vehicular trusses over the Missouri River. Since its completion in December 1929, the Plattsmouth Bridge has carried relatively heavy traffic on this strategically important interstate route.
The Plattsmouth Bridge is historically significant as a nationally important vehicular crossing of the Missouri River--the oldest extant Missouri River highway bridge into Iowa. It is technologically significant as a noteworthy example of cantilevered truss construction [adapted from Fraser 1990].
- Through truss toll bridge over Missouri River on old US 34 at Plattsmouth
- Plattsmouth, Cass County, Nebraska, and Mills County, Iowa
- Open to traffic
- Built 1929; rehabilitated 2008
- - Modjeski & Chase (Consulting engineers)
- Omaha Steel Works of Omaha, Nebaraska (Superstructure)
- Union Bridge & Construction Co. of Kansas City, Missouri (Substructure)
- Cantilevered Warren through truss
Length of largest span: 402.3 ft.
Total length: 1,420.3 ft.
Deck width: 20.0 ft.
Vertical clearance above deck: 15.0 ft.
- Approximate latitude, longitude
- +41.00094, -95.86685 (decimal degrees)
41°00'03" N, 95°52'01" W (degrees°minutes'seconds")
- Approximate UTM coordinates
- 15/258882/4542821 (zone/easting/northing)
- Quadrangle map:
- Pacific Junction
- Inventory numbers
- IA 35690 (Iowa bridge number)
BH 23841 (Bridgehunter.com ID)
- Inspection (as of 11/2015)
- Deck condition rating: Satisfactory (6 out of 9)
Superstructure condition rating: Poor (4 out of 9)
Substructure condition rating: Poor (4 out of 9)
Sufficiency rating: 22.3 (out of 100)
- Average daily traffic (as of 2012)
- March 19, 2017: New photo from Daniel Barnes
- November 1, 2014: Updated by Luke: Modified status
- March 17, 2014: New Street View added by Luke Harden
- March 17, 2014: New Street View added by Robert Elder
- September 14, 2012: New photos from Mark Frazier
- February 10, 2012: Photo imported by Luke Harden
- July 29, 2011: Updated by Luke Harden: Added description
- September 10, 2010: Updated by David Backlin: Scheduled for replacement 2013
- March 14, 2010: Updated by James Baughn: Removed duplicate listing, added Street View
- December 8, 2009: Updated by Brad J Williams: Corrected an Error, Bridge goes to Cass County, NE not Sarpy County, NE
- September 12, 2008: Updated by J.R. Manning: Updated Location
- June 16, 2008: New photos from Historic American Engineering Record
- HAER IA-67 - Plattsmouth Bridge
- J.R. Manning - thekitchenguy [at] sbcglobal [dot] net
- Brad J Williams - brad [at] bradwilliamsphotography [dot] com
- David Backlin - us71 [at] cox [dot] net
- Mark Frazier - mfrazier404 [at] gmail [dot] com
- Robert Elder - robertelder1 [at] gmail [dot] com
- Daniel Barnes