A curfew has been imposed in Houston where more than 13,000 people have been rescued after a catastrophic storm that is now the heaviest tropical downpour in US history.
With its flood defences strained, the crippled city anxiously watched dams and levees to see if they would hold until the rain stops.
Meteorologists offered the first reason for hope, with a forecast of less than an inch of rain and even a chance of sunshine.
But the human toll continued to mount, both in deaths and in the ever-swelling number of scared people made homeless by Storm Harvey.
The city's largest shelter was overflowing when the mayor announced plans to create space for thousands of extra people by opening two and possibly three more mega-shelters.
"We are not turning anyone away. But it does mean we need to expand our capabilities and our capacity," Sylvester Turner said. "Relief is coming."
In an apparent response to scattered reports of looting, the mayor imposed a curfew, which he later amended to run from midnight to 5am, instead of beginning at 10pm.
He told a news conference that there is no reason for people to be on the streets during those hours.
Police Chief Art Acevedo said that curfew violators will be stopped, questioned, searched and arrested.
The rescues went on, and federal and local agencies said they had lifted more than 13,000 people out of the floodwaters in the Houston area and surrounding cities and counties.
Louisiana's governor offered to take in Harvey victims from Texas, and televangelist Joel Osteen opened his Houston megachurch, a 16,000-seat former arena, after critics blasted him on social media for not acting to help families displaced by the storm.
The death toll from Harvey rose to at least 18 as the Harris County, Texas, forensic office reported three more fatalities.
They include an 89-year-old woman, Agnes Stanley, who was found floating in floodwater in a home, and a 76-year-old woman who was found floating in floodwater near a vehicle. Her name was not released.
A 45-year-old man, Travis Lynn Callihan, left his vehicle and fell into floodwaters, and was taken to hospital, where he died on Monday.
Family members and authorities have reported at least 18 deaths, although the bodies of some victims apparently swept away in the floodwaters have not been found.