By early afternoon, traffic was bumper-to-bumper on roads leading inland from North Carolina's Outer Banks as people tried to get out of the way of the 115mph Bonnie, which it was feared would hit the coast by daybreak today.
Many residents were unwilling to take the chance that the first hurricane of the Atlantic season would follow the path of some previous storms and take a last-minute turn out to sea.
Last Monday, Bonnie's path was so slow and wobbly forecasters were unsure if it would hit land. But by yesterday afternoon, the storm was centred about 330 miles south of Cape Hatteras and was pushing north-west at 16mph - three times faster than a day earlier.
Swimming was banned at beaches as far north as New York's Long Island as Bonnie kicked up dangerous surf up and down the east coast.
More than 310,000 people were ordered off North Carolina's coastal islands. About 220,000 more were told to leave South Carolina's two northernmost coastal counties.
The South Carolina governor, David Beasley, warned: "Anybody who does not abide by the mandatory evacuation, our law enforcement has been instructed to ask them their next of kin."
Many people were staying just long enough to protect their property. At Surf City, Chris Medlin was cutting plywood to cover the windows of his fishing store. "We've done this too many times to stick around," he said.
Farther out in the Atlantic, Hurricane Danielle moved toward the Virgin Islands with 80mph winds, and forecasters expect it to be as strong as Bonnie within days.
Rescue teams in south-west Texas were yesterday searching for 30 people reported missing after floods left a trail of death and destruction along the United States-Mexico border.
Authorities said at least 17 people died when heavy rains from the remnants of Tropical Storm Charley drenched the area, starting on Saturday. Del Rio, where seven people died, had 18in of rain in four hours on Sunday; the town's average annual rainfall is 17in.
The Rio Grande, which forms the border between Texas and Mexico and is normally placid enough for immigrants to swim across, became a mile wide, rising 22ft above flood stage. Across the Rio Grande from Del Rio, in Ciudad Acuna, at least six people died in the floods.
The area had been in the midst of a searing drought, with only five inches of rain in 1998, the National Weather Service said.