Thawing snowpack and heavy rains have brought historically high flooding to several Midwestern states and have led to thousands of evacuations.
Three people have died, including a man who officials say was trying to rescue strangers from freezing flood waters.
Record-breaking flooding in at least five states has led to emergency declarations. Several communities have been cut off from outside help.
It follows a powerful winter storm that slammed the US last week.
A hurricane-like weather phenomenon that scientists call a "bomb cyclone" hit the western Rocky Mountains and US Central Plains last week, showering snow and freezing rains on millions of Americans in Iowa, Nebraska, Wisconsin, Minnesota and South Dakota.
The National Weather Service said flooding would continue across parts of the Central Plains and Upper Midwest for the rest of the week.
President Donald Trump described the floods as "devastating" and said the White House would keep in close contact with state officials.
In a statement, Wisconsin Governor Tony Evers said "warm temperatures and rain the last few days have caused much of the heavy snowpack and ice to melt resulting in flooding, ice jams, and rivers and creeks to rise".
The Missouri River has reached record high levels in several locations, including in Iowa and Nebraska, which have been hit hardest by the flooding.
Residents in the towns of Bartlett and Thurman were ordered to evacuate on Sunday as levees were breached.
Three people have been killed, and two other men have been missing for days.