This is an Odd Duck for sure!
The "Sideways" verticals, which are sometimes seen on thru truss spans, are pretty rare for ponies. Also the floorbeam placement at mid-truss is uncommon for such a short span. The substructure definitely has a budget "Aftermarket" look about it.
They riveted the floorbeams into the the verticals directly, and did so above the lower chord (versus using hangers or riveted pin plates below the lower chord to attach floorbeams) which is why the deck is positioned correctly. Seems like the floorbeams might extend outside the verticals a little? Without further details, I can't tell but maybe this bridge used to be in an urban location with cantilevered sidewalks. Some of the lower chord eyebar heads look altered. A screwy looking bridge to be sure. Fairly heavy duty upper chord too.
This is a rather bizarre little bridge. For starters, the deck is mounted about halfway up the truss. In other words, the driving surface is about halfway between the top chord and the bottom chord. This means that the transverse floor beams are unusually tall for such a little bridge.
The built-up verticals are "sideways" which is not exceptionally uncommon, just a bit unusual. The lattice bars on the verticals are found only above the deck. Below the deck, the unusually tall floor beams fill the space where the lattice bars would continue. As a result, this bridge does not have u bolt hangers on the bottom chord. Instead, it looks to me that the sideways verticals more or less serve as the hangers.
Finally, this Bridge was either moved here or was retrofitted with non original bents. Unless my eyes are playing tricks on me, the end posts seem to overshoot these bents a bit. I would not be surprised if the construction date of circa 1920 refers to a modification date. To me, this bridge looks like it might have been built circa 1900. A date range of circa 1890 to 1910 seems reasonable to me.
A former urban setting makes sense. As soon as I stated looking at Nick's images, I began to suspect that this one is not in its original location.
I noticed those eyebar heads as well. I think that maybe a couple of other bridges that Nick visited might have had them as well. I need to go back and look through his entries.