In February 1873 the Van Buren County Board of Supervisors contracted with the Wrought Iron Bridge Company of Canton, Ohio, to build a major wagon bridge over the Des Moines River at Keosauqua. Comprised of four bowstring arch-truss spans, supported by massive stone piers with tapered upstream cutwaters, the Keosauqua was the county's first major all-iron structure. WIBCo used its patented, tubular bowstring design, completing the structure by September of that year. As a pivotal crossing at the county's center, the Keosauqua Bridge carried heavy wagon, and later automobile, traffic for some 65 years. By the late 1930s, however, the original bridge showed signs of wear and created a bottleneck to traffic with its narrow roadway. In 1938 the Iowa State Highway Commission designed a replacement superstructure for the bridge, to be placed on new concrete caps that flared over the original stone abutments and piers. Designated Federal Aid Project 165-FGH, a contract for the construction of the new trusses and pier extensions was awarded to the A. Olson Construction Company of Waterloo, Iowa, in August 1938. Using steel fabricated by the Inland Steel Company of East Chicago, Indiana, Olson completed the replacement bridge in 1939 for $86,141. One of the original 1873 arch-trusses was moved to a rural crossing in Davis County (and has been recently demolished). The 1939 bridge has functioned in place, without substantial alteration.
As one of Van Buren County's oldest and most heavily trafficked crossings, the Keosauqua Bridge has played a central role in the development of transportation and commerce in this southern Iowa county. For this the bridge is historically significant. In addition, the 1939 trusses are technologically significant for their uncommon Warren web configuration. The state highway commission typically employed straight-chorded Warren designs for its pony trusses and Pratts--with both straight and polygonal upper chords--for its through trusses. In the mid-1930s, ISHC apparently experimented with Warren through trusses as an alternative to the Pratts, building a handful of these atypically configured bridges across the state. Although rigid-connected Warren trusses from the 1930s are hardly more technologically adventuresome than their Pratt counterparts, they are noteworthy in Iowa for their relative rarity. It is not known how many of these Warren through trusses featured polygonal upper chords, but the Keosauqua Bridge is notable as the only such polygonal-chorded Warren remaining in Iowa today. It is thus distinguished as a now-unique structural type developed by the state highway commission in the 1930s [adapted from Fraser 1991].
- Lost through truss bridge over Des Moines River on IA 1 in Keosauqua
- Keosauqua, Van Buren County, Iowa
- Replaced by new bridge
- Built 1939, Replaced 2007
- - A. Olson Construction Co. of Waterloo, Iowa
- Inland Steel Co. of East Chicago, Indiana (Iron/Steel Manufacturer)
- Iowa State Highway Commission of Ames, Iowa (Design)
- Polygonal Warren through truss
Length of largest span: 151.9 ft.
Total length: 615.2 ft.
Deck width: 24.0 ft.
Vertical clearance above deck: 14.3 ft.
Posted to the National Register of Historic Places on May 15, 1998
- Also called
- IA1 Des Moines River Bridge
- Approximate latitude, longitude
- +40.72741, -91.95896 (decimal degrees)
40°43'39" N, 91°57'32" W (degrees°minutes'seconds")
- Approximate UTM coordinates
- 15/587913/4509018 (zone/easting/northing)
- Quadrangle map:
- Inventory numbers
- IA 50180 (Iowa bridge number)
NRHP 427542 (National Register of Historic Places reference number)
BH 14567 (Bridgehunter.com ID)
- January 28, 2015: New photo from Luke
- October 22, 2013: Photo imported by Luke Harden
- May 14, 2013: New photo from Luke Harden
- May 4, 2013: Updated by Luke Harden: Added builders
- July 29, 2011: Updated by Luke Harden: added NHRP info
- May 24, 2011: Updated by Jason Smith: This bridge has been replaced