I know that in St. Louis there are three similar truss bridges crossing the Mississippi: Merchants, McKinley, and MacArthur. I believe all three are Pennsylvania truss. Each of them has three spans, and each span is over 500' long (over 600' on the MacArthur). I think the McKinley is the most elegant of the three, though no longer a railroad bridge.
Courtesy of Bridgehunter:
http://bridgehunter.com/photos/35/69/356935-L.jpg
This dead-on shot of a single span may be helpful!