Nishnabotna River Bridge, Spanning Nishnabotna River, Manilla, Crawford County, IA

Significance: The availability of steel for domestic purposes like bridge building was severely limited during World War II. Most of the counties of Iowa, including Crawford County, turned to timber to fulfill their short-span bridge construction needs. In May of 1945, however, heavy flooding washed out 27 bridges and culverts throughout the county. It was decided to build replacement spans using steel. The Des Moines Steel Company was hired to design and fabricate the bridges. Forced to economize with material they turned to a bridge form that was popular in the 1860s and 1870s: the bowstring arch-truss. Although lacking the lateral stability of later bridge forms, the bowstring offered outstanding structural efficiency. During the period of the 1860s and 1870s thousands of bowstring arch-trusses were built throughout the nation. In a time of national crisis this once popular bridge form again supplied the solution. The Nishnabotna bridge is an excellent example of this series of bridges built during the war.
Unprocessed Field note material exists for this structure: N220
Survey number: HAER IA-48
Building/structure dates: 1945 Initial Construction
National Register of Historic Places NRIS Number: 98000801