Millions of evacuees from the Gulf Coast emerged from emergency shelters and motel rooms Saturday to be told by officials to stay put and not head home, but a massive return migration began anyway, despite widespread power outages, flooded roadways and long lines for gasoline. And in many counties to the south and east of here, it was still raining heavily.

As many as 3 million people from coastal Texas and Louisiana fled from Hurricane Rita, causing enormous traffic jams on the highways Thursday and Friday. Some had to drive as far north as Oklahoma to find shelters or lodging. In Dallas, the Red Cross shelters in the city convention center and in Reunion Arena were turning away evacuees late Friday. The east Texas city of Lufkin saw its population of 35,000 triple, and after official shelters filled, local churches and a rodeo arena began taking in desperate stragglers.

In Houston, Mayor Bill White on Saturday pleaded with residents not to return to the city, warning them that 675,000 households were without power, that gasoline was scarce and roads were liable to become overwhelmed. Texas Gov. Rick Perry (R) amplified the message of "don't worry, don't hurry" and said evacuees should stay put for a couple of days at least.

But with the news that Houston and Galveston had been spared severe damage, a lot of folks were packing coolers and luggage back into their cars and trucks for a return journey. "We're going home," said Don Walker of Houston, as he loaded the family SUV at a downtown hotel with his children and their coloring books. "I know there's going to be traffic. But we got all day, and we got a full tank of gas and so we're just going to take it easy but make our way back." Walker said he had plenty of supplies at home in his garage in west Houston and was prepared to wait there for the lights to come back on.

There were news reports that some of the interstates leading back to Houston were filling with traffic. As many as 200 service stations in the Dallas-Fort Worth area were running low on gasoline or had run out, and tanker trucks to resupply them had not arrived at several stations visited Saturday afternoon.

"You got to do what you got to do," said Brian Hamilton, 25, of Houston, who visited one station only to see a sign telling him "NO GAS!" Hamilton said he had a quarter-tank left and was willing to risk it by driving south and seeing what he could find. Hamilton and his girlfriend had spent Friday night sleeping in their pickup truck at a supermarket parking lot. His plan? "If we start to run out of gas, I'll get on a back road and beg, borrow or buy some from a boy wants to make himself 50 bucks."

Some evacuees from coastal Louisiana appeared to be less gung-ho to hit the road as reports came in of widespread flooding there. At an emergency shelter at the county jail here, where evacuees were sleeping on bunk beds in cells, several have been here for weeks, since Hurricane Katrina hit. They said they would probably have to wait a little longer. (The jail is still operating and filled with inmates, who have been moved to a different section of the facility, away from storm evacuees.)

"As soon as I can, I'm going to be gone, but I hear we're still under water, so we're stuck," said Charles Divincenti, of St. Bernard Parish south of New Orleans, who watched his trailer float away during Katrina. "I was holding onto the flagpole in my brother's yard," said Divincenti, 65, a retired deep-sea diver on Gulf Coast oil rigs. "They came and got us with a boat." The last thing he did before Katrina hit, he said, was release his 11-foot albino python from its cage. The snake will probably be okay, Divincenti said, but he is not sure what is happening to his 12 brothers and sisters. "We're scattered to the winds."

While the evacuees who fled Houston and Galveston have homes and jobs to return to, those who left Beaumont and Lake Charles were desperate for information. "We don't know what it looks like," said Gloria Hernandez, 41, of Beaumont. She and her sister and her children were staying with friends of friends, and Hernandez drove down to the Red Cross shelter at Reunion Arena Saturday afternoon hoping to get answers. "But I don't know what they know." Officials at the shelter advised her to remain in Dallas. She said she probably would. "I think I need to go and get some sleep."

Lindsey Polk, 12, with her dog, Scout, in the family vehicle wait to return to Galveston from Houston, where the family stayed during the storm. Cars line up on Interstate 10 to return to Galveston after the storm passed through the area.