Confirmed this line and bridge was Chicago, Milwaukee St. Paul & Pacific, now abandoned awaiting trail development.
this is not a Chicago, Burlington & Quincy ether although Chicago, Burlington & Quincy use it also but it was Chicago, Milwaukee, St. Paul and Pacific as per all maps i could find
This is not the Canadian National bridge; the through-truss bridge shown here originally belonged to the Chicago, Burlington & Quincy (later, Burlington Northern). It is currently owned by the Illinois Railway and also used by Canadian PACIFIC's Dakota, Minnesota & Eastern Railraod. This bridge is slated to be closed to rail traffic in 2012, with trains being rerouted around it on the Illinois Central (now CNRR) bridge a short distance to the south.
Side note: The CB&Q through-truss bridge shown here replaced a covered bridge, probably in the late 1800s. Covered railroad bridges were extremely rare in the Midwest.
At the western edge of the Milwaukee Road bridge in Rockford is a rock where a plaque used to be. The base says 1964. Does anyone know what the plaque commemorated?