As Florence churned slowly towards the coasts of North and SC as a Category 2 hurricane, federal and state officials issued final appeals to residents to get out of the path of the "once in a lifetime" weather system.
Florence could do more than $170bn (£130bn) of damage and affect almost 759,000 homes and businesses, says analytics firm CoreLogic.
A simulation weather video is showing what the life-threatening Hurricane Florence storm surge might look like if it reaches a frightening nine feet (2.7m). "I am frightened about what's coming". Cooper and South Carolina Gov. Henry McMaster told more than 1 million people who were directed to leave that if they don't evacuate, no one will come to save them.
At least 88,000 people were without power in North Carolina with the brunt of the storm yet to come, according to the state's emergency management agency.
Duke Energy, the nation's No. 2 power company, said Florence could knock out electricity to three-quarters of its 4 million customers in the Carolinas, and outages could last for weeks.
The mayor of Carolina Beach, North Carolina, said authorities have stopped allowing traffic to the island via the only bridge between the island and the mainland.
Once a Category 4 hurricane with winds of 140 miles per hour (225 kph), the hurricane was downgraded to a Category 1 on Thursday night.
The storm's center was about 50 miles south of Morehead City at around 11 p.m. (0300 GMT Friday).
More than one million people had been ordered to evacuate the coasts of North and SC and Virginia and thousands moved to emergency shelters, officials said.
The expected high winds and slow movement of the hurricane as it comes ashore are likely to make rescue efforts in flooded areas challenging, senior US Defence Department officials say.
Even if you know nothing about hurricanes, an unavoidable sense of doom and destruction overtakes you when you look at this image of Hurricane Florence as it moves inexorably toward North and SC.
The result: prolonged storm surge, wind and rain.
According to the NHC's forecast discussion at 12 p.m. on September 13: "The subtropical ridge to the northeast and east of Florence is now well-established between Bermuda and the US mid-Atlantic region and extends westward into Virginia and the central Appalachians".
A state of emergency has been declared in five coastal states - North Carolina, South Carolina, Georgia, Maryland and Virginia.
Some residents have ignored calls to evacuate. It had long lines on Thursday.
Browning's choice to stay in the hurricane warning zone wasn't easy, she said, but she "could not find anywhere to go".
North Carolina Governor Roy Cooper said, 'The time to prepare is nearly over.
Instead, they drove 240km inland to his mother's house in Durham. "The anxiety level has dropped substantially", Epperson said.