The massive storm was roaring through the Gulf of Mexico toward one of the largest American cities and the centre of the US oil industry.
The path of Rita, downgraded to Category 4 hurricane when its winds fell to 150 mph (240 kph), shifted northward and appeared to be headed slightly east of Galveston and Houston, the National Hurricane Centre said yesterday.
But the storm remained unpredictable.
“I don’t think anyone in the Gulf Coast is out of harm’s way,” said David Paulison, acting director of the Federal Emergency Management Agency.
Drivers waited hours to move on jammed highways from Texas into Louisiana as coastal residents, heeding the lessons of Hurricane Katrina, headed inland to escape one of the most intense storms on record.
“It’s an absolute nightmare,” said John Griffin, 37, who turned back to Houston with his wife and two daughters after trying for several hours to drive farther inland.
As Rita neared, Exxon Mobil said it was closing the biggest US oil refinery in Baytown, Texas and another in Beaumont, 90 miles (144 km) east.
Environmentalists warned that the stretch of coast threatened by Rita is home to 87 chemical plants, refineries and petroleum storage installations, raising the possibility that the storm could cause a major oil spill or toxic release.
South-eastern Texas is also home to more than a dozen sites deemed hazardous.
NASA evacuated Johnson Space Centre and transferred control of the international space station to the Russians. Storm surge projections have put most of the NASA space centre, situated about 20 miles south-east of downtown Houston, underwater in the event of any hurricane above Category 2.
Rita’s projected track, which on Wednesday threatened to clobber Galveston and Houston, slowly moved up the coast. The revised path would spare the Gulf Coast’s largest population centre the storm’s full brunt.
“We may dodge a bullet in Houston, Texas,” Governor Rick Perry said.
“But I’d rather sit in traffic for eight to 12 hours than take a chance it doesn’t change.
“We’re talking about people’s lives here.”
Louisiana Governor Kathleen Blanco urged coastal communities to evacuate as forecasts indicated Rita would come closer than previously thought.
Rita was expected to continue losing some steam as it neared land, but was still forecast to hit Texas late today or early tomorrow as no less than a Category 3 storm with winds of up to 130 mph (209 kph). A hurricane warning was in effect from Port O’Connor, Texas, to Morgan City, Louisiana.
President George W Bush, widely criticised for his response to Katrina almost four weeks ago, described it as “a really big storm”.
“Officials at every level of government are preparing for the worst,” he said.
Mr Bush will visit Texas today to look at emergency preparations.
The last major hurricane to strike Houston was Category 3 Alicia in 1983. It flooded downtown Houston, spawned 22 tornadoes and left 21 people dead.
Although Houston is 60 miles inland, it is a low-lying, flat, sprawling city whose vast stretches of concrete cover clay soil that does not easily soak up water. The city is beribboned with seven bayous that overflow their banks even in a strong thunderstorm.
Scientists fear the storm surge from a hurricane could cause the bayous’ currents to reverse, pushing water back into the city and swamp poor, Hispanic neighbourhoods in the city’s southeast.
Houston is home to the biggest concentration of Katrina refugees from Louisiana. Rita forced many of them to pick up and leave again.
Among them was Tommy Green, 38, evacuated from his New Orleans-area home during Katrina. “I’m trying to hold up,” he said. “I’m tired of all this. It’s tough.”