The bridge this entry is for is behind the bridge in the foreground
Public Domain: Published Prior to 1923
BH Photo #339315
This page is for the road bridge adjacent to the railroad bridge, and the build date/builder come from a trade magazine article you can find linked below in the sources section, as well as maps.
The page for the railroad bridge is: https://bridgehunter.com/ia/des-moines/bh72509/