Old Chain of Rocks Bridge

The bridge takes its name from the Chain of Rocks, a stretch of rock ledges and rapids that made the Mississippi above St. Louis so dangerous that by the 1940s it was the last obstacle to a nine-foot channel from St. Paul to New Orleans. The Corps of Engineers answered with a canal around the reach and, in the 1960s, a low-water dam just below the bridge that keeps most of the rocks under water. The city's waterworks went in here from 1887, and the riverbank park beside it drew picnickers by streetcar and, from 1923 to 1977, an amusement park.

Private investors built the bridge as a toll crossing, at a cost of $3 million, and it opened in January 1929. Halfway across it turns 22 degrees, a bend forced during construction by a water intake and by bedrock that could not carry piers where the straight line wanted them. The company went bankrupt by 1932. In the 1930s Bypass US 66 was routed over it so through traffic could skirt downtown. Madison, Illinois, which came to own it, lifted the tolls in 1966, the year the new Interstate 270 bridge opened just upstream, and the old bridge closed to cars on February 25, 1970.

For almost thirty years it stood empty. In 1998 the trails group Trailnet leased it and opened it to walkers and cyclists, and since 2014 Great Rivers Greenway has run it as the north end of the Mississippi Greenway. It was listed on the National Register in 2006.