This looks to me like a pin-connected bedstead that has had the lower part of its end pieces encased in concrete. Being pin-connected, it surely is older than 1920, but maybe 1920 was when it was moved here and "reinforced" by the concrete. And being the "oldest" record for this bridge, that "becomes" the date of the bridge, even though the truss existed somewhere else first.
Just curious if anyone else thinks this bridge is older then the 1920 ca date given by the NBI