Despite widespread estimates that as many as 1 million evacuees fled Southern California’s wildfires, the number of people displaced from their homes at any one time appears to have been substantially lower.

At the height of evacuations Tuesday morning in San Diego County, officials said nearly 350,000 households had received automated emergency phone calls warning them to evacuate. Using 2000 census data, emergency response officials estimated that they had ordered 513,000 of the county’s 3.1 million people out of their homes and advised 12,000 more to leave.

Within hours, however, some of those evacuations were lifted. More San Diego residents were ordered to leave on Wednesday, but by then, unknown numbers of earlier evacuees already were back home.

That pattern is one of several reasons why the widely publicized estimates of evacuation numbers are probably exaggerated.

Another reason is that not everyone obeyed evacuation orders.

Authorities cannot force people from their homes, although they can prevent them from returning once they leave. For those who leave, there is no central registry, meaning that official counts of evacuees are guesses based on population data.

On Monday, Los Angeles County Sheriff’s Department patrol cars drove along High Sierra Trail north of Saugus, blaring mandatory evacuation orders. Within minutes, many residents said they planned to stay.

“It’s better now than it was last night,” said Beth Kray. The fire, she said, had been “on the ridge right behind. We couldn’t get a wink of sleep.”

San Diego’s sprawling Scripps Ranch development was another place where fire-tested residents weighed their options. Some neighborhoods emptied out nearly completely, with residents clogging traffic as a few die-hards remained to guard their homes. On other blocks, as many as half the residents stayed, according to neighbors. Four years ago, hundreds of homes in the development were lost in the massive Cedar fire.

On one stretch of Loire Avenue, a man whose home burned to the ground in the Cedar fire wasted no time packing up. A neighbor a few doors down, whose roof caught fire last time, stayed put.

“In 2003, we saw our house burning on television,” said Paul Devincenzo, who stayed overnight at another residence he owns in the city. He returned to Scripps Ranch on Tuesday afternoon. “This time we evacuated with mixed feelings. You know the danger of staying behind, but you also want to stay and do something to save your house.”

Dick Curtis, 71, said he and several neighbors on Crystal Oaks Way in Scripps Ranch decided to stay until the flames came too close for comfort, rather than venture to unknown territory at Qualcomm Stadium.

Curtis, who has a respiratory condition, said the air was better inside his house than it would have been in the parking lot of the stadium or at other locations.

“We agreed to all leave en masse at the first sign of sirens,” he said. “And for anybody who was asleep, we were going to bang on doors and honk our horns.” The sirens, however, were silent.

In addition to the San Diego County evacuations, Orange County ordered 43,000 residents from their homes. In Los Angeles County, Sheriff Lee Baca said a total of 21,500 residents were told to evacuate. In San Bernardino, officials ordered 15,000 to leave their homes.

Numerous news organizations, including The Times, had estimated the total number evacuated at more than 800,000, with many outlets placing the number displaced at 1 million. Some San Diego officials have made the comparison to the Gulf Coast’s mass evacuation when Hurricane Katrina struck two years ago, when 1.2 million left Greater New Orleans ahead of the approaching storm, according to a study by Louisiana State University.

“We’ve evacuated more people than were evacuated in Katrina,” San Diego County Sheriff Bill Kolender said Wednesday.

That statement now seems imprecise.

Transportation analysts for the Automobile Club of Southern California said that because evacuation orders were issued over a period of days, it was unlikely that half a million people were moving all at once.

“If there had been 500,000 people on the road at one time, there would have been headlines everywhere,” said spokeswoman Carol Thorp. “We have to remember that people were hitting the road over several different days and at different times.”

The evacuation before Katrina was complicated in part because 120,000 New Orleans residents did not have cars in which to leave town. Many had no place to go to out of town, said Ivor Van Heerden, director of the Hurricane Public Health Center at Louisiana State.

In San Diego County, officials noted, people leaving fire areas had numerous routes available. Most residents in the largely affluent suburbs have cars, and much of the county remains livable and largely unaffected by fire.

Even if only half of those ordered out of their San Diego County homes had left, however, more than a quarter of a million people would still have been on the move earlier this week. Where they all landed remains uncertain.

At the peak of evacuations, 27,000 people had checked into public shelters, including Qualcomm Stadium, according to emergency operations officials. With approximately 10,000 available hotel rooms in the county, evacuees quickly filled them, Others pitched tents in parking lots, slept in their cars or took hotel rooms as far north as Los Angeles. Many other residents were able to stay with nearby friends or relatives.

Other San Diego County residents left the area. On Wednesday, as some orders were lifted, the California Department of Transportation received numerous calls from San Diegans who had gone to Las Vegas and Arizona, wondering if the roads were open for a trip back home.

Ed Cartagena, a spokesman for Caltrans in San Diego, moved his own family to Las Vegas when flames approached his Paradise Hills neighborhood.

“I just took them out of town,” Cartagena said Wednesday. “They’re in Las Vegas right now.”

City and county officials are proud of the orderly way in which a population the size of Portland packed up children, pets and possessions to find shelter.

“People heeded our calls,” said Bill Harris, spokesman for the city of San Diego. “We saw people evacuate when they were told to do so . . . and our rescue personnel were able to get to the fire lines. They were not impeded by traffic.”

gil.reza@latimes.com

sharon.bernstein@latimes.com

megan.garvey@latimes.com

Times staff writers Robert J. Lopez, Alex Pham, Garrett Therolf and Richard Winton contributed to this report.