(CNN) -- Hurricane Florence has the potential to cause "massive damage" to parts of the southeastern and mid-Atlantic United States -- and not just in the coastal areas where the storm aims to make landfall Friday morning, officials warned.
More than 1 million people face mandatory evacuation orders Tuesday in coastal areas of Virginia, North Carolina and South Carolina, as one of the strongest hurricanes to churn toward the eastern seaboard in decades -- currently a Category 4 storm -- nears shore.
Tropical-storm-force winds are due to reach the coasts of North and South Carolina on Thursday morning, and hurricane-force winds may be felt around Thursday night, ahead of an anticipated Friday landfall.
Powerful storm surges and winds will pose deadly threats, as will long periods of heavy rain. Beyond the Carolinas and Virginia, the threat of inland flooding extends into next week to parts of Tennessee, Georgia, West Virginia, Ohio, Maryland and Pennsylvania, forecasters said.
Tim Terman and his wife live in Southport, near Bald Head Island, North Carolina.
Their family members have been pressuring them to evacuate, he said, but they are staying put -- for now.
"Once you leave, (it will be) hard to get back in to check on damage," he told CNN. "My home is all my wife and I have, materially speaking, a lifetime of stuff." They say their house is about 20 feet above sea level.
They will make their final decision Wednesday, Terman said.
• As of 2 p.m. ET Tuesday, Florence's center had maximum sustained winds of 130 mph and was about 845 miles east-southeast of Cape Fear, North Carolina.
• Florence is expected to strengthen Tuesday, though it may weaken to a Category 3 storm by landfall around Friday morning, likely in the Carolinas, current forecasts show.
• Still, it will "be an extremely dangerous major hurricane" through landfall, the National Hurricane Center said.
• President Donald Trump declared an emergency in North Carolina, allowing it to access federal funds. "I think that any amounts of money, whatever it takes, we're going to do," Trump said.
• Among the storm's threats later this week: Life-threatening storm surges -- up to 12 feet -- along the coasts and generally up to 30 inches of rain through early next week over parts of the Carolinas and Mid-Atlantic states.
• The storm's center may move very slowly inland -- meaning rain for days in some places. "This thing is going to stop, and it's going to rain -- and it's going to rain. ... We could see 3 feet," CNN meteorologist Chad Myers said Tuesday afternoon.
• Mandatory evacuations have been ordered for most of the South Carolina coastline, in Edisto Beach as well as from Charleston County northeast to Horry County. They've also been ordered for parts of coastal North Carolina and Virginia.
• Though not every coastal area in North Carolina was under mandatory evacuation Tuesday morning, "I believe that people should be evacuating the coast of North Carolina," Federal Emergency Management Agency Administrator Brock Long told CNN's "New Day."
• Hurricane and storm surge watches extend from Edisto Beach, South Carolina, northward to the North Carolina-Virginia border, including the Pamlico and Albemarle Sounds, the National Hurricane Center said. Those areas are at risk for hurricane conditions and "life-threatening inundation, from rising water moving inland from the coastline" during the next 48 hours, the NHC said.
Residents prepare to flee and hunker down
"This will be a storm that creates and causes massive damage to our country," Jeff Byard, Federal Emergency Management Agency associate administrator, said Tuesday morning.
"It is going to be ... a long-term recovery," Byard said. "This is not going to be a storm that we recover from in days."
Residents along the coast boarded up their homes, formed long lines at gas stations and emptied the shelves of hardware stores and supermarkets this week as they prepared for Florence's arrival.
On Ocracoke Island along North Carolina's Outer Banks, Kelley Shinn's partner woke her up at 3 a.m. Tuesday and told her to pack. He figured the forecasts were too ominous to stay.
They and their 12-year-old packed her Jeep with clothes and other things, and within hours, they took a ferry to the mainland, then struck out for her father's home in Ohio.
"It's surreal to think we may have nothing to go home to," she told CNN. " ... We've never left for a storm before. But a storm surge of 20 feet could easily wipe this island out."
John McGowan, a resident of a town just west of Wilmington, said Tuesday he planned on staying through the storm -- but filled his vehicle with gas in case he changes his mind.
"I'll make an evaluation tomorrow (Wednesday) afternoon. If that thing is still coming at us at about 120 mph, I may change my mind," he said.
In Wilmington, Anita Harrell said she waited 90 minutes at a Home Depot on Tuesday to get plywood, intending to board up her home and business.
The store, she said, was starting to run out, and was limiting each customer to 12 pieces.
The storm intensified rapidly earlier in the week: It became a hurricane over the Atlantic on Sunday, and by Monday morning, it had grown to a Category 3 storm. About an hour after the Category 3 upgrade, it was reclassified as Category 4.
States of emergency declared in four states
One year after major storms ravaged the Gulf Coast and Puerto Rico, officials warned those in Florence's path not to underestimate the threat the storm poses.
States of emergency were declared in the Carolinas; Virginia; Washington, DC; and Maryland, where some coastal areas are still recovering from summer storms.
"We are hoping for the best and preparing for the worst," Maryland Gov. Larry Hogan said, noting that Florence could cause catastrophic flooding in his state.
North Carolina Gov. Roy Cooper on Tuesday urged people to make preparations and heed evacuation orders, warning that electrical service could be lost for several days, and days of heavy rain could lead to severe flooding in many areas.
"The time to hope Hurricane Florence away is gone," he said.
In South Carolina, traffic in all lanes of Interstate 26 from Charleston to Columbia has been directed away from the coast, South Carolina Gov. Henry McMaster said.
Traffic also has been directed away from the coast on parts of US 501, McMaster said.
In Virginia, mandatory evacuations began Tuesday morning for about 245,000 residents in a portion of Hampton Roads and the Eastern Shore area.
National Guard soldiers are being mobilized in the affected states.