In 1993 , the Mississippi River experienced major flooding during the Great Flood of 1993 . North of St. Louis , all bridges from the McKinley Bridge up to the Keokuk Bridge were shut down due to flooding at one point or another . The I-270 bridge , despite having lower than normal clearance over the Mississippi River , remained open . The majority of the other bridges that were closed had flooded approaches , however , all of the approaches on I-270 were built on high ground and remained above water . This led to some of the worst traffic delays on the bridge during this time , especially during peak periods at the height of the floods
Great Flood of 1993
Great Flood of 1993
New Chain of Rocks Bridge