I am in agreement with both Anthony and Nathan. I deliberately used a wide date range, knowing that the occasional post-1900 bridge featured decorative portals - ie the 1902 Long Shoals Bridge in Bourbon, Co. Kansas.
But yes, I think pre-1900 is a reasonably safe bet.
The portal bracing with circles in them are definitely more akin to around 1890 than anything post 1900.
Agreed. My guess, closer to ca. 1890 based on the lightweight decorative bracing.
This bridge looks much older than 1930. I am guessing 1890-1910.