This bridge type is a very unusual type of Bascule bridge known as a Scherzer Rolling Lift Bridge. This particular bridge carries a branch of the Canadian National Railroad over the Rainy River between Ranier, MN, and Fort Frances, Ontario, Canada. This unique bascule type features a curved pair of rockers on the rotation end of the bridge, which ride on a horizontal track to raise the bridge--essentially, the bridge rocks back, much like that of a rocking chair.
The upper chord of the bridge starts out high at the rotation end and slopes uniformly downward to meet the end posts at the lifting end of the bridge, giving it a somewhat wedged shape. The bridge features a Warren truss configuration. Photographing this beautiful structure may be a problem, as it doesn't look like any major roads are near the Minnesota side, and crossing into Canada and dealing with the border patrol doesn't seem to be worth the trouble. The deck plate girder on the Canada side is very long and would hamper photographing the main truss anyway. As a side note, this is the third busiest international railroad crossing in the nation.
Warren through truss bascule bridge over Rainy River on Canadian National Railroad