One postcard ad claims this was the wooden truss bridge.
This article gives some interesting history on the Shawtown Bridge, although I'm not quite sure what to make of the dates as it seems to indicate that the 1884-1925 bridge at the site was a large wooden truss rather than the metal span pictured in the postcard on this page.
https://www.wisconsinhistory.org/Records/Property/HI41817?ms...
It looks to me like a regular iron/steel truss with a wooden deck rather than an actual timber truss, but I could be wrong as the photo is not real close up.