The Chicago and North Western Railway's Kinzie Street railroad bridge (also known as the Carroll Avenue bridge) is a single leaf bascule bridge across the north branch of the Chicago River in downtown Chicago, Illinois. At the time of its opening in 1908 it was the world's longest and heaviest bascule bridge. Previous bridges on the same site included the first bridge to cross the Chicago River, Chicago's first railroad bridge, and one of first all-steel bridges in the United States.
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Links: en.wikipedia.org, virtualglobetrotting.com