Nashville Mayor Karl Dean: rainfall levels at a record high
Parts of Nashville, Tennessee, have been evacuated after a levee protecting the southern city sprang a leak.
Nashville landmarks like the Country Music Hall of Fame and the symphony centre are surrounded by water.
Officials say at least 27 people were killed in three southern states over the weekend.
Seventeen people were killed in Tennessee, most of them drowning in flash floods, while the others died in Mississippi and Kentucky.
In Nashville, more than 13in (33cm) of rain fell over two days, almost doubling the previous rainfall record.
Nashville's Opryland Hotel on the banks of the Cumberland was flooded after the river breached its levees.
A hotel spokeswoman said it would remain closed indefinitely, and 1,500 of its guests were evacuated to a high school.
Hickman county, to the east of Nashville, requested large quantities of water after their waste water and water treatment plants broke down.
Nashville Mayor Karl Dean inspected the damage from the air and said it was worse than he had expected.
"This situation is going to require a very large recovery process. The safety of some of our infrastructure is questionable," he told the Tennessean newspaper.
Kentucky Governor Steve Beshear has requested federal assistance to deal with the storm damage.