* More than 50 killed by storm, including at least 11 in US
* Millions still without power
* Residents return to parts of Florida Keys
* Authorities working to restore basic services
* Irma could be long-term boost to economy-Mnuchin


Some residents of the Florida Keys archipelago allowed back Tuesday found homes that Hurricane Irma's high winds had shredded like soda cans, while the death toll rose in the second major hurricane to hit the United States this year.

Irma, one of the most powerful Atlantic hurricanes on record before it arrived in the United States, killed 43 people in its rampage through the Caribbean and at least 11 in Florida, Georgia and South Carolina.
On Islamadora Key, one of just three islands where authorities allowed people to return on Tuesday, the aluminum walls of trailer homes had been ripped open by the storm, exposing insulation, bedrooms and kitchens to the sunlight.
More substantial structures, like churches and businesses, showed less damage, although access to harder-hit islands remained closed. Roadsides were littered with mangrove branches, motorboats and even a hot tub.
A local Florida official said there had been more deaths yet to be reported, particularly on the Keys, where Irma arrived on Key Cudjoe as a Category 4 hurricane with sustained winds of up to 130 miles per hour (215 km per hour) on Sunday.
Local authorities told around 90,000 residents of Miami Beach and people from some parts of the Keys they could go home but warned it might not be prudent to remain there.
"This is going to be a frustrating event. It's going to take some time to let people back into their homes particularly in the Florida Keys," said Brock Long, administrator of the Federal Emergency Management Agency. The island chain curves southwest from Key Largo to Key West, linked by bridges and causeways.
Some 6.7 million homes and businesses, representing about 13 million people, were still without power in Florida and nearby states on Tuesday, utility companies said, as they scrambled to get the lights back on in one of the biggest power restoration efforts in US history.
Florida's largest utility, Florida Power & Light, said western parts of the state might be without electricity until Sept. 22.

'So many areas' flooded

The city of Jacksonville, in Florida's northeast, was recovering from heavy flooding.
"There are so many areas that you would never have thought would have flooded that have flooded," Florida Governor Rick Scott told reporters after a helicopter tour of the area.
Irma devastated several Caribbean islands en route to Florida. It destroyed about one-third of the buildings on the Dutch-ruled portion of St. Martin island, the Dutch Red Cross said on Tuesday.
Irma hit the United States soon after Hurricane Harvey, which plowed into Houston late last month, killing about 60 and causing some $180 billion in damage, largely through flooding.
Monroe County Commissioner Heather Carruthers said on Monday that people had been killed in the Keys, which are a popular tourist destination and have nearly 80,000 permanent residents, but she did not have specific figures.
The US aircraft carrier Abraham Lincoln was off Florida's east coast and two amphibious assault ships were en route to help in the Keys.

Deaths during cleanup

Several major airports in Florida that halted passenger operations due to Irma began limited service on Tuesday, including Miami International, one of the busiest US airports.
Insured property losses in Florida from Irma were expected to run from $20 billion to $40 billion, catastrophe modeling firm AIR Worldwide estimated.
US Treasury Secretary Steven Mnuchin told an investor conference in New York that the storm would ultimately boost the economy by sparking rebuilding.
"There clearly is going to be an impact on GDP in the short run, we will make it up in the long run," Mnuchin said. "As we rebuild, that will help GDP. It's too early to tell what the exact estimates will be, but I think it won't have a bad impact on the economy."
Several of the deaths caused by Irma came as people started cleaning up and making repairs.
A 55-year-old man died Monday in Tampa, Florida, while using a chainsaw in a tree during storm cleanup, the Hillsborough County Sheriff's Office said.
A man died in Worth County, Georgia, on Monday while repairing the roof of a shed during sustained winds of 42 mph (67 kph) with gusts up to 70 mph (112 kph), a National Weather Service report said.
A man was found dead in Winter Garden, Florida, after being electrocuted by a downed power line, local police said.
One man in South Carolina was killed by a falling tree limb and another died in a traffic accident, officials said.
Irma was downgraded to a tropical depression on Monday and would likely dissipate Tuesday evening, the National Hurricane Center said.
The center was monitoring another hurricane, Jose, which was spinning in the Atlantic about 700 miles (1,130 km) west of Florida. About 2-1/2 months remain in the Atlantic hurricane season, which starts in June.