During the Great Flood of 1993 , the New Chain of Rocks Bridge carrying I-270 over the Mississippi River was the only bridge open from St. Louis to Keokuk , Iowa , at one point . ( All other bridges from the McKinley Bridge to the Keokuk Bridge were closed at the peak of that flood . ) The last major construction project on I-270 occurred from 1995 to 1998 . Both the Missouri Department of Transportation ( MoDOT ) and IDOT upgraded I-270 to modern standards from Lilac Avenue to I-255 . However , this section of I-270 is still at two lanes in each direction
Great Flood of 1993
Great Flood of 1993
Interstate 270 (Missouri–Illinois)