Could be they are going off the age of the piers instead of the age of the superstructure itself. It is definitely misleading as a lot of companies used existing piers that weren't damaged too badly by floods to save money. Ohio is known for cutting corners on bridge construction that way, and it may have contributed to the replacement of Philo and the closure and eventual replacement of Gaysport.
Too many. I gather that 1900 and 1920 are pretty much default dates for when they just don't know when a bridge was built....or as in this case, it probably refers to them not knowing how old the abutments are since the truss itself is of welded construction and clearly much newer than 1900.
NBI definitely needs to improve on that 1900s thing. I wonder how many times that got overused.
This bridge is going to be replaced in July per this news article sadly, showing Muskingum County's hatred for trusses continues https://whiznews.com/2022/06/27/bagley-road-closure/