The Bridge was the most famous crossing of Route 66 over the Mississippi. Its most notable feature is a 22-degree bend occurring at the middle of the crossing, necessary for navigation on the river. The name comes from a "chain" of rocks crossing the Mississippi just below the bridge — an exposure of bedrock creating rapids in the river. Originally a motor route, it now carries walking and biking trails over the river. The bridge was added to the National Register of Historic Places in 2006.