The Illinois National Guard was ordered into action and hundreds of people urged to flee rising floodwaters, as the death toll from days of heavy rain in the US Midwest mounted.
Swathes of the United States have been buffeted in the last week by tornadoes, storms and torrential rain, while the US East Coast has seen unseasonably warm weather over the holiday season.
Missouri and Illinois have been particularly hard hit from the record-breaking and relentless deluge in the past week.
The death toll from the flooding in the Midwest rose to 22 after a man's body was recovered in Missouri, ABC News said. Fifteen of the dead were in Missouri and seven in Illinois.
There were growing fears for southern Illinois, where the rising Mississippi River reportedly topped a levee, putting several towns and rural communities at risk.
Hundreds of people were urged to evacuate.
Bruce Rauner, governor of Illinois, tweeted, "I have ordered Illinois National Guard soldiers into active duty to aid local efforts to save lives and mitigate flood damage in Southern IL."
Forecasters warned that southern US states were in increasing danger in the days to come.
"Major flooding is occurring or forecast on the Mississippi and Ohio rivers and tributaries in Missouri, Illinois, and Kentucky, with record flooding at several locations," the National Weather Service said.
"Major flooding is also occurring on the Arkansas River and tributaries in Arkansas. Floodwaters will move downstream over the next couple of weeks, with significant river flooding expected for the lower Mississippi into mid-January."
There was some relief, however, in the St Louis area of Missouri, where flooding was at last receding.
