Maps from 1888 show the competed Great Northern line connecting Willmar to Marshall via Granite Falls while maps from 1887 show the mainline ending at Willmar. This dates the river crossing to 1887. I suspect that the piers are of 1887 vintage, but the bridge has likely been replaced once since it was new in order to accommodate ever heavier railroad locomotives. The riveted construction and the style of beams, made from crisscrossed metal tabs, date the bridge to have been built well before WWII.
The bridge crosses the Minnesota River at an angle heading northwest and southeast. From the southeast side, there is an embankment that carries the rail above the flood plain. Two through truss spans cross the main river channel. This is followed by a length of pony plate girder bridge, and then a third truss span that is again about 135 feet long. That truss is followed by a short section of conventional trestle which completes the remaining part of the estimated 800 foot long river crossing.
The photo above is a profile view of the BNSF bridge at Granite Falls as seen from a riverside park located upstream on the south side of the Minnesota River. The third bridge truss span is not visible from this location. In addition, the north end of the bridge appears to be difficult to get to without trespassing or using a boat.