Parts of the Florida Keys, the low-lying islands which bore the brunt of Hurricane Irma when the category-four storm struck on Sunday, have reopened.
Entry is being restricted to residents and business owners as work continues to clear roads and check the state of bridges linking the islands.
Nearly 6.9 million homes were without power in Florida, Georgia, North Carolina, South Carolina and Alabama.
Irma, which has since rapidly weakened, is being linked to 11 deaths in the US.
Seven people died in Florida, three in Georgia and one in South Carolina, according to US media.
The storm also left a trail of destruction in the Caribbean, where nearly 40 people were killed.
French President Emmanuel Macron has arrived in the region and is to visit devastated French islands, while UK Foreign Secretary Boris Johnson is heading to the British Virgin Islands.
Both France and Britain have been criticised for not doing enough to help their nationals in overseas territories affected by the hurricane.
Dutch King Willem-Alexander spent Monday night on the Dutch side of St Martin, an island shared between France and the Netherlands.
He told the NOS public newscaster: "I have seen proper war as well as natural disasters before, but I've never seen anything like this."
Florida Governor Rick Scott used the same word - "devastation" - after flying over the Keys on Monday.
"I just hope everybody survived," he said. "It's horrible what we saw."
"We saw a lot of boats washed ashore and we saw any, basically, any trailer park there overturned."
The Federal Emergency Management Agency estimates one in four homes in the Keys has been destroyed and that 60% were damaged.
Thousands of people ignored calls to evacuate last week, and clung on in the dangerously exposed islands during the storm.
However, Governor Scott added: "I didn't see the damage I thought I would see." Storm surges had turned out to be "not as bad as we thought", he said.
Teams are still working to clear Highway 1, the road connecting most of the inhabited islands, and bridge inspections are continuing.
Some residents were allowed into the towns of Key Largo, Tavernier and Islamorada on Tuesday morning, authorities in Monroe Country said.
They were warned that services on the islands were limited: most areas were still without power and water, mobile phone signals were patchy and most petrol stations were still closed.
The US aircraft carrier Abraham Lincoln has arrived off Florida and other navy ships were in the area on Tuesday to help distribute food to the Keys and evacuate residents.
In Jacksonville, Mayor Lenny Curry said 356 people had to be rescued amid record-high storm surges and flooding, the Florida Times-Union reported.
A Jacksonville Pizza Hut sparked online backlash after a manager threatened to punish employees who evacuated too early for Irma.
"You cannot evacuate Friday for a Tuesday storm event!" the restaurant's manager told employees in a notice, which was shared online.
Jacksonville officials began ordering a mandatory evacuation for parts of the city on Friday.
In a statement, Pizza Hut said the manager who posted the notice did not follow company guidelines.
Other parts of the state escaped the storm lightly compared to the Caribbean islands.
"The storm surge flooding in Miami is a mere fraction of what would have happened if the core of the storm had been further east," Rick Knabb, former director of the National Hurricane Center, said in a tweet.
The storm was downgraded as it moved north towards Atlanta, Georgia, with maximum sustained winds of 35mph (56km/h), the National Hurricane Center (NHC) said in a statement.
Another hurricane, Jose, has been weakening over the western Atlantic, with swells due to affect parts of Hispaniola (the island split into Haiti and the Dominican Republic), the Bahamas, and the Turks and Caicos Islands, later this week.