At least 22 people have died and thousands more have been forced to leave their homes after a deluge caused rivers and creeks to burst their banks across Tennessee and a number of neighbouring states.
The overflowing Cumberland River shut down bars and clubs in Nashville's tourist district, drove 1,500 guests from the Opryland hotel and closed schools and businesses.
Nashville mayor Karl Dean urged residents to conserve water because one of the city's treatment plants had to be shut down after more than 30 cm of rain fell.
"There are lots of flooded streets and highways and road damage" across central and western Tennessee, said Missy Marshall of Tennessee Emergency Management.
A block away from the Opryland complex, the Schermerhorn Symphony centre bailed out its basements.
Around Nashville, numerous shopping centres were underwater, including a complex housing the local National Public Radio station which was forced off the air.
Fourteen people died in Tennessee, including one in a tornado. Two people died in Kentucky and six in neighbouring Mississippi, state officials said.
President Barack Obama called Tennessee governor Phil Bredesen and Kentucky governor Steve Beshear and pledged a quick federal response to requests for support and expressed condolences for the loss of life, the White House said.
Some victims were found in submerged vehicles or inundated homes, while others were swept away in flooding that officials said was the worst in the area in decades.
Hundreds of residents had to be rescued, many by boat. Several state buildings in Nashville were closed. Weakened or leaking levees led authorities to evacuate some neighbourhoods.
Farther south, the fast-rising Loosahatchie River spilled out of its banks and led to evacuations in Waverly Farms, Tennessee, the Memphis Commercial Appeal said on its website.
Mississippi was hit by violent spring weather for the second weekend in a row after 10 people died in a powerful tornado that tore through Yazoo City.
As they tried to cope with the water and winds, state officials were also making preparations along coastlines for an oil slick from a massive spill in the Gulf of Mexico.
"That's three disasters," said emergency management spokeswoman Nikki Presley.
Reuters