Photo taken by Jason Smith
ocated on the outskirts of the small town of Klondike, this long-span through truss crosses the Big Sioux River on the border between Lyon County, Iowa, and Lincoln County, South Dakota. The Klondike Bridge is comprised of a concrete-decked Pratt through truss, with Warren pony truss approach spans on both ends. Concrete abutments and piers support the three trusses. The first bridge was built here in 1901, but as traffic on this regionally important crossing increased over the succeeding years, that structure eventually proved inadequate. In August 1913, the Lyon County Board of Supervisors contracted with the Western Bridge and Construction Company of Omaha, which had built virtually all of the county's trusses for a number of years, to fabricate and erect a replacement structure here. Western began excavating of the concrete substructure soon thereafter and, using steel rolled by the Cambria mills in Pittsburgh, erected the three-span truss later that year. For the pony trusses, Western used the newly developed design standard of the Iowa State Highway Commission. ISHC had not yet engineered a standard for the 160-foot through truss, however, and for this Western apparently used a truss of its own design, featuring both pinned and riveted connections. The structure itself was completed late in 1914, its fills early in 1915. Since its completion, the Klondike Bridge carried interstate traffic in unaltered condition until recently, when it was superseded by another crossing and is now closed to vehicular traffic.
Before the standardization of bridge design in 1913, the individual counties were left to their own devices for bridge construction. Some of the more prosperous counties could afford a full-time staff engineer or could hire consulting engineers for their bridge design but most relied on the bridge companies that bid competitively for bridge construction projects. The Iowa State Legislature changed this process radically when it passed the Brockway Act in the spring of 1913, requiring the counties to use ISHC standards and effectively eliminating the design-build role of the regional and state bridge companies. The proliferation of standard plans occurred quickly in 1913 and 1914, so that the transition period was actually quite brief. In a few cases, though, in which no standard plans yet existed and ISHC did no produce special designs, non-standard structures were approved for construction. This is the case with the Klondike Bridge. Built using both standard and non-standard designs, the Klondike Bridge is historically significant for its representation of this brief transitional period in Iowa highway bridge construction. It is also significant for its role as an important interstate crossing. In well-preserved condition, the Klondike Bridge is an important resource form the formative period of Iowa's highway system [adapted from Fraser 1992].
- Through truss bridge over Big Sioux River on 180th Street southeast of Sioux Falls
- Lyon County, Iowa, and Lincoln County, South Dakota
- Open to pedestrians only
- Built 1913-15 by the Western Bridge and Construction Co. of Omaha. Replaced by modern bridge in 1977.
- - Western Bridge & Construction Co. of Omaha, Nebraska
- Approaches: Riveted Warren pony trusses
Main span: Pin-connected, 9-panel Pratt through truss
Posted to the National Register of Historic Places on May 15, 1998
- Approximate latitude, longitude
- +43.38934, -96.52223 (decimal degrees)
43°23'22" N, 96°31'20" W (degrees°minutes'seconds")
- Approximate UTM coordinates
- 14/700682/4807033 (zone/easting/northing)
- Land survey
- T. 99 N., R. 48 W., Sec. 20 (Centennial Township)
- USGS topographic map
- Inventory numbers
- NRHP 98000510 (National Register of Historic Places reference number)
BH 13926 (Bridgehunter.com ID)
- October 11, 2012: Updated by Jason Smith: Added categories "Big Sioux River", "A-frame portal"
- September 11, 2011: Updated by Luke Harden: added description
- May 28, 2011: New Street View added by Sheldon Wiens
- October 5, 2009: New photos from Jason Smith
- October 10, 2005: Posted photos from Jason Smith
- Jason Smith - JDSmith77 [at] gmx [dot] net
- Sheldon Wiens
- Luke Harden - lukemh9 [at] gmail [dot] com