With winds of 175 mph (280 kph), the Category 5 hurricane churned across the Gulf of Mexico on a course that was expected to take it ashore late today or early on Saturday.

Having learned a lesson from Hurricane Katrina's assault on Louisiana and Mississippi last month, city officials along the Texas coast told residents to clear out and arranged for buses for those who needed help. Residents of the island city of Galveston, Corpus Christi and low-lying parts of Houston 50 miles inland were among the 1.3 million Texans told to evacuate. Houstonians fleeing their city created bumper-to-bumper traffic jams on interstate highways that lasted well into the night.

New Orleans, still staggering after being flooded by Katrina, was taking no chances this time. Mayor Ray Nagin said two busloads of people had been evacuated already and 500 other buses were ready. Texas Gov. Rick Perry, who told people along a 300-mile (483 km) stretch of coast to leave, said computer projections were prepared for city officials so they could see what could be left underwater after being hit by Rita's storm surge.

“Between Katrina and our preparations for this, people understand this isn't something you're going to play around with,” Perry told CNN. He said 5,000 Texas National Guard troops were on standby and 1,000 Department of Public Safety officers were along evacuation routes, ready to move in after Rita's landfall. Shelters for 250,000 evacuees were being established in Huntsville, College Station, San Antonio and Dallas.

Corpus Christi Mayor Henry Garrett said the evacuation of his city was inspired by Katrina and was going smoothly. “One of the things we realized that we needed to do here in Corpus Christi was to look at our evacuation plan,” he said in a CNN interview. “We felt we needed to evacuate a couple of days earlier than what we had planned on.”

As of 5 a.m. EDT (0900 GMT), Rita's center was about 515 miles (830 km) southeast of Galveston and 615 miles (990 km) east-southeast of Corpus Christi with hurricane-force winds that extended 70 miles (110 km) from its center. It was moving west-northwest at about 9 mph (15 kph), the US National Hurricane Center said.

The storm developed into the third most intense Atlantic hurricane on record as measured by internal pressure, the hurricane center said. Rita's maximum sustained winds rising to 175 mph (281 kph) over the warm waters of the Gulf matched the peak strength over water of Katrina, which hit land as a Category 4 storm with 145 mph (233 kph) winds.

The hurricane watch was issued for the US Gulf Coast from Port Mansfield Texas, to Intracoastal City, Louisiana, a 575-mile (925-km) stretch that covers almost all the Texas coast. After criticism for a slow response to Katrina, President George W. Bush declared emergencies for Texas and Louisiana as Rita approached.

US Homeland Security Secretary Michael Chertoff said authorities had positioned supplies and were checking on communications systems. The government sent Coast Guard Rear Adm. Larry Hereth to Texas to coordinate the response.

A FEMA spokesman said Rita was not expected to re-flood New Orleans if the storm stayed on its current westward course. Financial markets reacted immediately to news the storm had gained strength, with the prospect of more destruction and oil-supply interruptions affecting everything from stocks and the dollar to oil prices.

Oil companies just starting to recover from Katrina evacuated Gulf oil rigs as Rita moved closer. Four Texas refineries were shut down, even as four refineries remained shut in Louisiana and Mississippi after Katrina.

Recovering after Katrina

The Mexican government issued a tropical storm watch for the country's northeast coast from Rio San Fernando northward. The last major hurricane to hit Houston was Alicia in 1983, a Category 3 storm that killed 22 people. Tropical Storm Allison in 2001 caused extensive flooding in the city and killed more than 40 people across the United States.

Hurricane Rita strengthened on Wednesday into a powerful, intensely dangerous Category 5 storm as it headed toward the Texas coast and prompted evacuation orders for more than a million people.

The hurricane center said Rita was “a potentially catastrophic” Category 5 hurricane with maximum sustained winds rising to 175 mph (281 kph) over the warm waters of the Gulf of Mexico. That matched the peak strength over water of last month’s devastating Hurricane Katrina, which hit land as a Category 4 storm with 145-mph (233-kph) winds. A hurricane watch was issued for the US Gulf Coast.

Mark BABINECK