The Chain of Rocks Bridge carried travelers over the Mississippi River between Illinois and Missouri from 1936 until 1955.  This was the third bridge for Route 66.

The bridge was originally privately built as a toll bridge in 1929 at a cost of $2.5 million (twice the original estimated cost). Later, it was turned over to the city of Madison, Illinois.

The bridge's name comes from the rock ledges just under the river's surface that made this part of the Mississippi river extremely dangerous to navigate. This "chain of rocks," spans to the north of St. Louis for about 17-miles and narrows the river.

The Illinois side of the bridge is located on Chouteau Island. The bridge's Missouri side reaches the main shoreline.

The bridge is 5,353-feet in length, 93-feet high, and has a 22-degree bend in the middle. The 40-foot wide roadway is nearly 60-feet above the water.

In 1967, the New Chain of Rocks Bridge carrying Interstate I-270 opened about half-a-mile upstream. One year later, the old Chain of Rocks bridge was closed and essentially abandoned. 

In the 1980s, a group called Trailnet began cleanup and restoration of the bridge. In 1999, the bridge linked more than 300-miles of trails and bike paths on both sides of the river.

Today, it's still closed to vehicle traffic, but is a popular Route 66 attraction as well as a walking and biking path.

It was listed on the National Register of Historic Places in 2006.