South Third Avenue Bridge, Marshalltown, Marshall County, IA

Significance: The South Third Avenue bridge in Marshalltown is one of fifteen known concrete rainbow arch bridges in Iowa. It is considered an important structural form in the development of reinforced concrete technology and illustrates Iowa's significant civil engineering heritage. It was designed by the March Engineering Company of Des Moines, Iowa, for the City of Marshalltown. James B. Marsh also was granted the U.S. patent for this bridge style. Also considered important is the fact that the interior reinforcing varies from that specified in the original patent and, in some details, varies from the design plans.
Survey number: HAER IA-8
Building/structure dates: 1920 Initial Construction