The old Chain of Rocks Bridge spans the Mississippi River on the north edge of St. Louis, Missouri. The eastern end of the bridge is on Chouteau Island, (part of Madison, Illinois), while the western end is on the Missouri shoreline. Its most notable feature is a 22-degree bend occurring at the middle of the crossing. Originally a motor route, the bridge was for a time the route used by U.S. Route 66 (US 66) to cross over the Mississippi, but the bridge now carries only walking and biking trails over the river - and the New Chain of Rocks Bridge carries vehicular traffic to the north. The old route to the bridge is now called Chain of Rocks Road and ends near Roman Road. Parking is available at the start of the now pedestrian route. The bridge was added to the National Register of Historic Places in 2006.[2]