Iowa Highway Commission blueprints, April 1928
I have no idea how many overhead truss bridges remain on paved roads in Iowa, but they are few and far between nowadays. The one I knew of for sure, on old US 218 in Janesville, is now history.
The bridge was a silent signal of one of Iowa’s greatest fights by a small town against the Highway Commission when it came to highway routings. Originally, IA 40, later US 218, followed Main Street and Barrick Road, using a bridge from 1882 to cross the Cedar River. The 1928 paving plan called for the highway to skirt the edges of Janesville, and residents fought so hard against it the IHC let them be, well, sticks in the mud.
It took a year and a half, but the IHC’s plan won out. A contract for a new bridge over the Cedar River was let in September 1929, with construction over the winter. (Bridgehunter is way off on the construction date. “Old IA 969” refers to a very short-term designation of the route between when the four-lane 218 opened and the state turned over the road.)
The paving through Janesville, completed in 1930, was the last link in a continuously paved US 18/218 from Emmetsburg to Waterloo, and from there to Chicago via US 20, or by that fall, to Des Moines via IA 59 and US 30 or 32.
(h/t Austin Draude)