Historic Bridges

Details

The first county roads in Dickinson County included a route extending westward from Spirit Lake and running east between East Okoboji and Spirit Lakes, then south and west to Gar Outlet. Establishing the latter two routes involved bridging the county's two most strategic crossings: the straits between East and West Okoboji Lakes and between East Okoboji and Spirit Lakes. Prior to construction of bridges, travelers were faced either with fording the crossings or with journeying several miles around the lakes. In December 1859 Dickinson County hired local contractors to build the county's first bridges at these points. 

The configuration of the lakes, and the requirements of steam boat traffic between them, led to a series of failed attempts to bridge the narrows. After 50 years of false starts and short-lived wooden swing bridges, the board of supervisors opted for a more permanent solution on June 15, 1909, when they contracted with the Clinton Bridge and Iron Works of Clinton, Iowa, to fabricate and erect a new steel bridge. Completed that year for $1,550, the new swing span consisted of an 80-foot, rigid-connected pivot truss with a six-foot-wide sidewalk, resting on concrete and masonry abutments. The bridge and the adjacent county road were later incorporated into a U.S. highway and placed under the aegis of the Iowa State Highway Commission (ISHC). Both would carry heavy traffic over the next twenty years. The 1909 truss was replaced with a fixed-span concrete girder structure in 1929. Sometime after that, Dickinson County moved the 1909 truss to this rural crossing in Okoboji Township, erecting it on a timber pile bent substructure. Here it has functioned in place as a fixed-span truss. Timber piles have been inserted under the truss's panel points, and the bridge has recently been closed to traffic, but the truss itself remains unaltered.

The Okoboji Bridge is historically significant for its pivotal role in the development of Dickinson County. One of the county's earliest crossings, it clearly encouraged settlement and contributed to the region's socioeconomic development. From its first rudimentary timber span in 1860, through timber and steel lift and wing spans, the Okoboji Bridge illustrates five decades of technological evolution. The truss itself is technologically noteworthy as a small-scale swing span - the only one of its kind known to remain in Iowa. The bridge's atypical bearing condition is reflected in the truss's web configuration. The center panel, upon which the bridge rested on its pivot pier, features an inverted V diagonal pattern. The truss is thus effectively a hybridization of Pratt and Warren technologies. Although its locational and structural integrity have been compromised substantially by the move, this steel superstructure is still a significant remnant of early transportation [adapted from Fraser 1992].