Mike: Unlike Ohio, Michigan has not traditionally built modern welded highway truss bridges. So the county probably thought of this as a unique structure in Michigan. I think they chose a truss for aesthetic reasons (even though it looks nothing like the historic bridge it replaced). However, the bridge is no longer unique in Michigan. I'm not sure that we are going to turn into Ohio with welded trusses everywhere, but this bridge was replaced with a truss: https://historicbridges.org/bridges/browser/?bridgebrowser=b... and then another stringer bridge, this one in Eaton County, was replaced with a truss and the trusses blocked the view of the road for a nearby intersection resulting in many accidents. https://www.lansingstatejournal.com/story/news/local/2018/12...
Gee, the county likes showing this one off, eh?
http://www.ccrc-roads.com/ - right on the main page.
At least, I'm pretty sure this is the one...
Also, I'm thinking the NRHP listing isn't meant to be reflected here, though I'm not sure if the Register itself has been updated to reflect that the original bridge (which is/was on the Register) is no longer there.
Could have even boiled down to being as simple as "replace a truss with a truss"...despite the two being different types of trusses.
See also: The two posted examples in Mason County, and Holy Island Road in Charlevoix County.