Swollen rivers and streams were pushed to heights not seen since the massive 1993 floods, causing Illinois to transfer an unknown number of inmates from a state prison and declare disasters governor in seven counties and prompting Missouri's governor to activate the National Guard to help divert traffic away from submerged roads.
At least 20 deaths over several days in Missouri and Illinois were blamed on flooding, mostly involving vehicles that drove onto swamped roadways, and at least two people were still missing Wednesday.
Record flooding was projected in some Mississippi River towns after several days of torrential rain that also caused sewage to flow unfiltered into waterways.
In southern Illinois, the Department of Corrections transferred an unspecified number of inmates from a state prison to other locations because of flooding risks.
Capt. Martin Malloy cited high water levels and fast currents in the river, which is a vital transportation hub for barges that carry agricultural products and other goods.