"The Rock Valley Bridge represents the culmination of an extensive concrete bridge construction program undertaken by Marshall County in the 1910s. It is the only span built by the county on the Lincoln Highway, America's first transcontinental route. This medium-span, reinforced concrete rainbow arch is a representative example of the hundreds of such structures designed and marketed by their inventor, Des Moines engineer James B. Marsh. Dozens of rainbow arches were built in Iowa in the 1910s, 20s, and 30s. Now only eleven remain, most in deteriorating condition."
Clayton B. Fraser Principal, FRASERdesign Loveland, Colorado 80537 October 1988 `
Length of largest span: 110.0 ft.
Total length: 158.0 ft.
Deck width: 20.0 ft.
Approximate latitude, longitude
+42.01330, -92.85625(decimal degrees) 42°00'48" N, 92°51'23" W (degrees°minutes'seconds")