Hurricane Laura’s winds battered Louisiana killing at least six people.
Winds of up to 150mph caused severe damage, with power cuts to more than half a million homes and a chemical fire from an industrial plant.
However, the feared 20ft storm surge was avoided as the hurricane, Louisiana’s biggest, tracked further east.
Laura has now been downgraded to tropical storm status.
The hurricane has since crossed into Arkansas. At 19:00 local time on August 27, the National Hurricane Center said the storm had weakened to maximum sustained winds of 40mph , but was still bringing heavy rainfall.
Louisiana Governor John Bel Edwards said the state “did not sustain and suffer the absolute, catastrophic damage that we thought was likely,” but stressed they had still suffered “a tremendous amount of damage” and warned people to remain vigilant.
He tweeted: “Now is not the time to let your guard down. #Laura has left hazards like flooded roads, downed power lines and displaced wildlife in our communities that no one should take lightly. Everyone needs to remain vigilant and be safe. #lagov #HurricaneLaura”
At least six people are known to have died after the storm crashed into the US, Gov Edwards told reporters.
Of those, four were killed by falling trees. One man drowned in a boat that sank and another died of carbon monoxide poisoning from a generator in his home, authorities said.
There was more structural damage from winds than anticipated, but the water damage was less than feared.
A barge had collided with a bridge in the city of Lake Charles, quite close to where a suspected “chlorine chemical fire” at an industrial plant was being attended by emergency services.
Governor Edwards said people should stay off the roads where possible, as outer bands of the storm were still causing high water levels and winds.
Some 1,500 people, including National Guard troops, are being deployed in rescue and clean-up missions.
President Donald Trump was briefed at the FEMA in Washington and said he would go to the area at the weekend.
The president said he had been prepared to postpone his speech at the RNC on August 27 to travel to the region but added: “We got a bit lucky. It was very big and very powerful but it passed quickly.”
Vice-President Mike Pence, who joined President Trump at FEMA, said: “While this was a major storm with devastating impact it was not as bad as it could have been.”
President Trump will visit the states affected at the weekend.
Laura and another storm, Marco, earlier swept across the Caribbean, killing 24 people.
Nearly 900,000 homes and businesses lost power as the storm hit the US.
Hurricane Laura was one of the strongest to ever hit the US Gulf Coast, striking as a category four with winds of up to 150mph .
Governor Edwards said it was even more powerful than Hurricane Katrina, the 2005 storm that devastated New Orleans and killed more than 1,800 people.
It made landfall shortly after midnight local time near the district of Cameron, in Louisiana. It tracked north, just east of the Texas-Louisiana border.
As yet, there have been no casualties confirmed in Texas. Governor Greg Abbott toured the area hit by the storm with the US Coast Guard on August 27, and said the state was “ready to help communities rebuild”.