The famous bend in the Chain of Rocks Bridge forms an angle of 22 degrees.
The bridge crosses the Mississippi River north of St. Louis, linking the Missouri shoreline with Chouteau Island in Illinois. Its unusual bend occurs near the middle of the crossing, making it one of the most recognizable engineering features associated with historic Route 66.
The angle was not simply decorative. Engineers included the bend because of a water intake and concerns that parts of the riverbed could not safely support the bridge’s weight. The bridge opened in 1929 and later carried a bypass alignment of U.S. Route 66 around the northern and western sides of St. Louis.
The old bridge no longer carries motor traffic. It is now used by pedestrians and cyclists, while the New Chain of Rocks Bridge carries vehicles farther north. The structure was added to the National Register of Historic Places in 2006, preserving an important Mississippi crossing linked to the Mother Road.