Even before the eye of the enormous storm hit shore, Ivan's wrath was felt on Thursday over a 640km stretch of the coast from New Orleans to Florida as vicious winds and heavy rain flattened trees and cut power to tens of thousands of people.
"Ivan is here," said Colette Boehm, spokeswoman for emergency management in Baldwin County, on the east side of Mobile Bay in Alabama.
"We are getting hurricane-force winds and they're still picking up. We have reports of rising water ... and of trees down and roofs coming off."
The centre of the storm was roaring over barrier islands near the Mississippi-Alabama border well before dawn, after a rampage in the Caribbean that killed 68 people.
Ivan is a Category 4 hurricane,
the second-highest level
Currently a Category 4 storm, Ivan earlier hit Category 5 and registered itself as the sixth most powerful Atlantic hurricane on record.
Towering waves, torrential rainfall and winds capable of splintering mobile homes were not the only danger. At least two people died in northwest Florida when about five tornadoes touched down and damaged or destroyed up to 70 buildings, including a fire station, police said.
Tens of thousands of people had evacuated in long streams of bumper-to-bumper traffic. In Mobile, Alabama - a city of 200,000 on a wide estuary directly in Ivan's path - Mayor Mike Dow said he had insisted his own family go north.
The storm has caused up to $2
billion in losses in the Caribbean
Ivan was expected to submerge downtown areas of the 300-year-old city founded by the French.
New Orleans, a city of 1.5 million people renowned for parties and jazz bars but sitting precariously below sea level, breathed a collective sigh of relief as the storm stayed east.
But officials remained nervous that Ivan's storm surge and rains could breach levies, overwhelm pumps and flood streets with a toxic brew of sewage, chemicals and water from the Mississippi River.
Oil production hit
Experts said Ivan could cause up to $10 billion in insured losses in the US on top of the $1 billion to $2 billion in losses in the Caribbean. Hurricanes Charley and Frances caused a collective $11 billion in insured damages after tearing through Florida in the past four weeks.
The insured losses do not reflect lost revenues for Florida's and the Gulf Coast's tourism industries. Nor do they include the economic costs of closing down oil rigs and refineries along the Gulf Coast, the source of a quarter of US oil and natural gas production.
1: Minimal, >153kph
2: Moderate, >177kph
3: Extensive, >209kph
4: Extreme, >249kph
5: Catastrophic, <>
At 1am EDT (0500 GMT), Ivan's eye was about 65km south of the Alabama coast at latitude 29.7 north and longitude 87.9 west, and moving north at about 19kph, forecasters said.
Ivan's top sustained winds were about 217kph, making it a Category 4 hurricane, the second-highest level on forecasters' five-level Saffir-Simpson scale of hurricane strength.