Conor Watkins' Ozark Mountain Experience
Article 4
Meet Me In St. Louis – Part II

The Old Chain of Rocks Bridge
And
The Confluence of the Missouri And Mississippi Rivers


This 22 degree bend served as a compromise between motor traffic
and river navigation.

The Old Chain of Rocks Bridge was constructed in 1929 as part of Route 66 and was financed by tolls.  In 1967, a new bridge carrying I-270 was constructed over the Mississippi and the old bridge was closed.  It sat, abandoned and decaying for 31 years.  During this time, the bridge was featured in the 1981 movie “Escape From New York” as the 69th Street Bridge.  The bridge also developed a bad reputation for crimes and violence including a rape and murder while it sat unused.  In 1999, the bridge was officially reopened for bicycle and pedestrian usage after renovations and security improvements.  Funding for the reopening of this bridge came from Trailnet (http://www.trailnet.org/trails.html#ocorb) and the Confluence Greenway Project (http://www.confluencegreenway.org/).  At one mile in length, the Old Chain of Rocks Bridge is the world’s longest pedestrian and bicycle bridge.  This bridge is located just north of St. Louis and is worth a look.


The Chain of Rocks Bridge as seen from the Missouri side.

The bridge’s most striking feature is its 22-degree turn in the middle.  This bend is a compromise due to the unique geology of the area and concerns about the navigation of river traffic around the bridge pylons.  Another interesting feature is the Chain of Rocks, a rocky area in the Mississippi that gave the bridge its name.  During low water, it looks as though there is a small waterfall in the Mississippi.  This feature used to wreak havoc with river navigation and has since been bypassed by the man-made Chain of Rocks Canal.

The Chain of Rocks Canal is a 47 mile long man made channel built through Illinois to bypass the Chain of Rocks in the late 1950’s and early 1960’s.  A below water dam was built across the Mississippi River below the Chain of Rocks to keep the river level high enough at the upstream end of the canal to provide adequate flows/levels for navigation within the canal.

Two gothic castle-like structures stand in the river just to the south of the bridge.  These structures serve as water intakes for the Chain of Rocks Water Treatment Facility, which opened in 1894 and is still in operation.  Excellent views of the St. Louis skyline and the Mississippi River are visible from the bridge.  Bald eagles may also be present during colder weather.  Bring the camera and binoculars when visiting this attraction.


These gothic water intakes were built in 1894 and are still in use.




Excellent views of the Chain of Rocks and St. Louis skyline may be seen from the
Chain of Rocks Bridge.

Both the strange 22-degree turn in the bridge and the Chain of Rocks owe their existence to glaciers.  During the last ice age, the Mississippi River was re-routed from its original channel in soft river sediment (farther to the east in present day Illinois) to its present channel over resistant (mainly limestone) bedrock.  The river has yet to wear down the bedrock and this feature is still a rough spot in the river.  If the bridge had been built straight, the engineers would have had to choose between two problematic routes.  One route would have put the bridge in a location where it couldn’t have been solidly founded on bedrock.  The other route would have posed problems to river navigation by not allowing barges to line up with the current, possibly causing them to collide with the bridge.  Although this bend was troublesome for motor traffic, it served as a compromise between geological and navigational concerns.

If a bridge were built in a similar location today, the extra expense to make the bridge straight would certainly be spent.  In the day of the Old Chain of Rocks Bridge, cars were narrower, slower, and traffic was less of a concern.  Today’s foundation piers can also be driven more efficiently and to deeper depths.  The old bridge is still structurally sound after all its years.  The unusual the bend in the fifteen-span bridge definitely adds character and doesn’t give pedestrians or cyclists any grief.

When the Chain of Rocks Canal opened, it carried all large navigational traffic around the Chain of Rocks and other rough spots in the river. When the 1967 bridge carrying I-270, known as the New Chain of Rocks Bridge, was built, navigation below was of little concern.  This enabled costs to be cut by constructing a bridge on a simple girder supported by 19 piers.  This design is cheaper to construct and maintain because a superstructure is absent.  This bridge is just north of the Old Chain of Rocks Bridge.


The Confluence of The Missouri and Mississippi Rivers

Just to the north of the Chain of Rocks Bridge, the Missouri River flows into the Mississippi.  The site where these two rivers come together was once located on private property, but is now open for all to see thanks to the Missouri Department of Conservation.  This tract of land in far north St. Louis County is known as Columbia Bottoms (http://www.conservation.state.mo.us/areas/areas/bottom/) and is available for cycling, hiking, and hunting.  Although the trails are not extremely rough, rugged shoes should be worn if hiking, and a mountain bike should be used if riding.  If the weather has been wet, expect mud.  Several trail routes to the confluence are available from the conservation area parking lot.  The shortest route is about six miles round trip on flat land.

It is a unique opportunity to be able to see two of the world’s largest rivers combining.  The water in the Missouri River flows about 3,740 miles from its headwaters in Montana through the Mississippi River and into the Gulf of Mexico.  This combined waterway is the world’s third longest with the Nile and Amazon ranking first and second respectively.  This feature also owes its existence to the continental ice sheets covering North America during the last ice age.  Before this time, the Missouri River used to flow through Canada and into the Hudson Bay.  The Missouri River’s modern day course is a good rough indicator of the southernmost advance of the continental ice sheets.


The confluence of the Missouri and Mississippi Rivers as seen from
Columbia Bottoms Conservation Area.

This land used to be privately owned farmland and the conservation department has continued to grow crops to attract game for hunters.  Ancient farm implements half buried in river sediment are interesting relics present along the trails.

To get to these locations from Rolla, take I-44 east towards St. Louis and get on I-270 heading north.  This large exit (exit 276) is about 90 miles east of Rolla and nearly impossible to miss.  Once on I-270, head north about 30 miles to Riverview Drive (Exit 34 - The last Missouri exit before Illinois).  I-270 is a loop around St. Louis and the highway will have turned due east by this exit.  If heading to the Chain of Rocks Bridge, turn right (south) on Riverview Drive.  The bridge is visible from this exit and a parking lot for the attraction is almost immediately off to the left. The bridge is only open on weekends during the winter.  Check http://www.trailnet.org for days and hours of operation.  In order to get to the confluence area, turn left (north) at the Riverview Drive exit and head north for several miles.  The Columbia Bottoms area will be marked off to the right just before the road takes a left turn and heads up a hill.  The close proximity of these two locations makes them excellent places for a day trip.  See “Geologic Wonders And Curiosities of Missouri” and “Climbing the Mississippi River Bridge By Bridge – Volume 1” by Mary Charlotte Aubry Costello, 1995 for more information on the above features.  Thank you to the good people writing on the MOCAVES list serve for providing some of the information presented in this article.



(Click for larger maps)
MAP KEY:
1.) Chain Of Rocks Bridge - Missouri Side Access
2.) Columbia Bottoms Conservation Area

(C) 2006 by Conor Watkins