I need to double check dates. The drawings I have were done by Illinois Central RR. They could have been done after construction. I also have some of the orignal Chicago Bridge & Iron "Bills of Wrought Iron/Steel" for components of the 1896 deck trusses. The word iron is crossed-out and replaced by the handwritten word "steel". The dates in these Bills of Wrought Iron/Steel should give an indication of date of construction.
I have the original drawings of this bridge (ink on linen). The deck truss section drawings are dated 1895 (built in 1896). The arch long span was built in 1932 to replace two 1896 sections, one of which was a draw or swing bridge. The piers were built in 1851 for a previous bridge and upgraded in 1896 and 1932.