Up to 90,000 people were urged to get out of the hurricane's path as the most powerful storm in four years to menace the mid-Atlantic coast loomed closer.
A hurricane warning went up late Tuesday from Cape Fear (search) to the North Carolina-Virginia state line, with a hurricane watch posted northward to Chincoteague, Va., including Chesapeake Bay.
Isabel's winds weakened during the day to around 105 mph, then picked up to 110 mph. Forecasters said little change was expected before the hurricane reaches land. Its projected course could take it straight into the Outer Banks early Thursday.
By Tuesday evening, grocery stores and restaurants were closed or shuttered and the Cape Hatteras Lighthouse was barred to visitors. The main beach highway, N.C. 12, was unusually barren of traffic and the beaches nearly desolate.
"Even a lot of old salts are bailing out," Brian Simmons said as he placed plywood across the window of Stoney's Seafood in Avon. "I don't know if it's some vibe they feel or something."
Coastal residents from South Carolina to New Jersey boarded up homes and businesses and stocked up on batteries, water and other supplies. The governors of North Carolina and Maryland declared states of emergency, allowing use of the National Guard and also alllowing them to seek federal disaster relief after the storm passes.
North Carolina Gov. Mike Easley urged residents to evacuate low-lying coastal areas.
"Now is the time to prepare," he said. "The course and intensity of this storm may change very quickly."
Thousands of tourists and others abandoned parts of North Carolina's Outer Banks as rough surf pounded the thin, 120-mile-long chain of islands.
Holly Barbour, vacationing from Wheeling, W. Va., said she and her family planned to head south to Myrtle Beach, S.C.
"Yesterday was so nice, we couldn't believe that a storm was coming," she said.
Some weather-tested residents treated the evacuation orders as just a suggestion. David Kidwell, a 64-year-old retiree, was staying put at his home in Kitty Hawk.
"If it was a 5, I'd be gone. If it was a 4, I'd be gone. But right now it's looking like a 2 or less," he said. "That's just nothing more than a big nor'easter as far as I'm concerned."
National Hurricane Center director Max Mayfield said he was concerned people were not taking the storm seriously enough because it had weakened to a Category 2.
"We need to get people's attention because this storm can cause a lot of damage and loss of life if people are unprepared," he said.
At 2 a.m. EDT, Isabel was about 480 miles southeast of North Carolina's Cape Hatteras, moving northwest at around 8 mph. It was down to a Category 2 storm on the Saffir-Simpson Hurricane Scale of intensity, from Category 5 over the weekend.
About 6,000 military personnel and their families on or near Langley Air Force Base in Hampton, Va., were ordered to leave.
After hitting land, Isabel could also spread heavy rain from North Carolina all the way to the New England states.
The last major hurricane to threaten the mid-Atlantic coast was Floyd in 1999. The Category 2 storm, with 110 mph winds, came ashore near Cape Fear, N.C., and continued along the coast into New England, causing 56 deaths and $4.6 billion in damage.
With would-be travelers encouraged to alter their plans in many cases, several airlines and Amtrak have eased their reservation policies ahead of Isabel's expected arrival.
Navy ships and submarines manned by 16,400 sailors headed out to sea from Norfolk, Va., and Earle, N.J., to ride out the storm and keep from being battered against their piers. Military aircraft were flown to airfields inland.
Colleges and universities in eastern Virginia, including the College of William & Mary, said they would close Wednesday for the rest of the week, and ordered students to leave.
In Simpson, N.C., a man preparing for Isabel accidentally burned his home down Monday when a generator he was testing caught fire.
In Atlantic City, N.J., Miss America Pageant officials said they were prepared to postpone Friday's Boardwalk parade and even the pageant itself on Saturday, if necessary.
Isabel even managed to interrupt plans for one of the most flood-friendly buildings around: a new museum encased in the stone vaults of Philadelphia's landmark 1815 waterworks.
Exhibits are made with water-resistant plastic, and electronic displays and video screens can be winched to the ceiling to escape floods. But with the Schuylkill River already swollen and inches below the exhibit's lowest floors, officials decided to postpone the museum's scheduled Friday opening.
Isabel kept home-improvement stores bustling as people bought everything from plywood to generators to chain saws. Lowe's estimated it sold 10,000 generators in nine days to coastal residents, and The Home Depot said it had trucks coming in from as far as Toronto and Texas to help meet demand.
Religious broadcaster Pat Robertson prayed on his Christian Broadcasting Network, based in Virginia Beach, that Isabel would turn from the coast. He asked God to put a "wall of protection" around Virginia Beach and the East Coast.
"In the name of Jesus, we reach out our hand in faith and we command that storm to cease its forward motion to the north and to turn and to go out into the sea," Robertson prayed on "The 700 Club."
The Associated Press contributed to this report.