Hurricane Matthew spared Florida's most heavily populated stretch from a catastrophic blow Friday but threatened some of the South's most historic and picturesque cities with ruinous flooding and wind damage as it pushed its way up the coastline.

Among the cities in the crosshairs were St. Augustine, Florida; Savannah, Georgia; and Charleston, South Carolina.

"There are houses that will probably not ever be the same again or not even be there," St. Augustine Mayor Nancy Shaver lamented as battleship-gray floodwaters coursed through the streets of the 451-year-old city founded by the Spanish.

Matthew - the most powerful hurricane to threaten the Atlantic Seaboard in over a decade - set off alarm as it closed in on the U.S., having left more than 300 people dead in Haiti.

In the end, it sideswiped Florida's Atlantic coast early Friday, swamping streets, toppling trees onto homes and knocking out power to more than 1 million people. But it stayed just far enough offshore to prevent major damage to cities like Miami, Fort Lauderdale and West Palm Beach.

One U.S. death was reported, that of a woman whose house was hit by a tree in the Daytona area.

"It looks like we've dodged a bullet," said Rep. Patrick Murphy, a Democrat whose district includes Martin County, just north of West Palm Beach.

Several northeastern Florida cities, including Jacksonville, were still in harm's way, along with communities farther up the coast. Authorities warned that not only could the hurricane easily turn toward land, it could also cause deadly flooding with its surge of seawater.

About 500,000 people were under evacuation orders in the Jacksonville area, along with another half-million along the Georgia coast.

"If you're hoping it's is just going to pass far enough offshore that this isn't a problem anymore - that is a very, very big mistake that you could make that could cost you your life," National Hurricane Center Director Rick Knabb warned.

St. Augustine, which is the nation's oldest permanently occupied European settlement and includes a 17th-century Spanish fortress and many historic homes turned into bed-and-breakfasts, was awash in rain and seawater that authorities said could top 8 feet.

"It's a really serious devastating situation," the mayor of the city of 14,000 said. "The flooding is just going to get higher and higher and higher."

Historic downtown Charleston, usually bustling with tourists who flock to see the city's beautifully maintained antebellum homes, was eerily quiet Friday, with many stores and shops boarded up with plywood and protected by stacks of sandbags.

The city announced a midnight-to-6 a.m. curfew Saturday, around the time the coast was expected to take the brunt of the storm.

The outer bands of the storm began lashing Savannah, a city that was settled in 1733 and has a handsome moss-draped historic district of Greek revival mansions and other 18th- and 19th-century homes.

Matthew was expected to bring winds of 50 to 60 mph that could snap branches from the city's burly live oak trees and damage the historic homes. And 8 to 14 inches of rain could bring some street flooding.

A small crew of workers Thursday set out to button up the Owens-Thomas house, one of Savannah's most prized architectural gems. The 1819 Greek revival mansion serves as a museum.

Sonja Wallen, a curator, said antique rugs and furniture were moved away from the home's more than 40 windows, many of them still with their original glass. Windows were fitted with plywood and other coverings, while sandbags were stacked at the basement entrance.

"It's basically a lot of little details - sandbags and duct tape around doorways where water can get in," Wallen said. "It's pretty much the same stuff you would do for any home."

Some of Georgia's best-known golf-and-tennis resort islands were expected to take the brunt of Matthew's storm surge, including St. Simons and Tybee.

On Tybee Island, where most of the 3,000 residents were evacuated, Jeff Dickey had been holding out hope that the storm might shift and spare his home. But as the rain picked up, he decided staying wasn't worth the risk.

"We kind of tried to wait to see if it will tilt more to the east," Dickey said. "But it's go time."

Mayor Jason Buelterman personally called some of the holdouts, hoping to persuade them to move inland.

"This is what happens when you don't have a hurricane for 100 years," he said. "People get complacent."

At 4 p.m. EDT, Matthew was centered about 35 miles east of St. Augustine and 45 miles southeast of Jacksonville, according to the National Hurricane Center. It was moving north at 12 mph with winds of about 115 mph. That was down from a terrifying 140 mph as the storm approached from the Caribbean.

Airlines canceled at least 4,500 flights Wednesday through Saturday, including many in and out of Orlando, where all three of the resort city's world-famous theme parks - Walt Disney World, Universal Studios and SeaWorld - closed because of the storm.

But things began getting back to normal, with flights resuming in Miami and other South Florida airports.

In areas the storm had already passed, residents and officials began to assess the damage.

Robert Tyler had feared the storm surge would flood his street two blocks from the Cape Canaveral beach. Tree branches fell, he could hear transformers exploding overnight, and the windows seemed as if they were about to blow in, despite the plywood over them.

But in the morning, there wasn't much water, his home didn't appear to have damage on first inspection, and his vehicles were unharmed.

"Overnight, it was scary as heck," Tyler said. "That description of a freight train is pretty accurate."