Of the 26 children in Ms. Siemssen's second-grade class, half did not return to class on Monday.

Maggie was gone, and so were Hannah and Michael and Megan and nine other children, and the empty desks and empty neighborhoods made an impression.

"It's like a ghost town," Jeremy Porter, 7, said as his class gathered to discuss their experiences in Hurricane Katrina for the first time. "There's no people left."

It was like that all across schools in Jefferson Parish, New Orleans's most populous suburb. Although most homes are relatively intact, many residents have stayed away: Only about half of the parish's 49,000 public school pupils were counted on the first day of classes since Hurricane Katrina struck in late August.

The widespread absences heightened fears that even though Jefferson Parish was spared the worst of Katrina's wrath, the community may be devastated all the same by a migration of jobs and people out of this metropolitan area of 1.3 million.

Many school parents who lived here and sustained little or no damage to their homes have relocated because their jobs in devastated portions of New Orleans have moved on, officials said. And many Jefferson Parish businesses that depended on New Orleans residents for customers or workers could leave as well.

"A lot of this area was untouched by the storm," said Jeffery Helmstetter, principal of Harahan Elementary School. "But folks lost jobs. The next dilemma is 'What do we do when the school system says you have to start cutting teachers?' It's not going to be pretty."

New Orleans Mayor C. Ray Nagin has estimated that roughly half of the city's 500,000 residents will not soon return. But economists say the devastation of New Orleans is likely to reverberate much farther -- even into those parts of the metropolitan area that suffered little physical damage.

"It's funny, because suburbs sometimes say they don't need the city and vice versa," said Geoffrey J.D. Hewings, director of the Regional Economics Applications Laboratory at the University of Illinois, who has studied economies after disasters. "But they do. There's a heck of a lot of cross-commuting that goes on for shopping and jobs."

As a result, he said, the city's woes are unlikely to be isolated. "You can't expect a huge metropolitan economy to pop up and reinvent itself," he said.

Jefferson Parish, which numbers about 500,000 people, sustained far less damage than New Orleans.

There was some flooding, and many homes still have sodden rugs piled up in front by the street. Many families in the flooded homes are not likely to return until the walls have been replaced.

But fewer than 2 percent of Jefferson Parish residences were damaged beyond repair, authorities have estimated, and electricity and water have been back for weeks.

In places such as Harahan, the vast majority of homes are habitable, officials said, but just over half the students came back for classes.

"Jefferson Parish is up and running with water and electricity, but so many people are still gone," said Libby Moran, a member of the parish school board. "That's why we're so worried: How many of them are gone permanently?"

A walk around Wilshire Plaza, one of the suburb's many strip malls, suggests how difficult it will be for businesses to recover.

The Shoney's is still closed, and so are a jewelry store, a children's clothing shop and a Weight Watchers office.

At stores that have reopened, managers said business had fallen off by 50 percent or more, probably because so much of their market entailed New Orleanians.

But the other big problem is workers. Signs saying "Now Hiring" or "Now Hiring All Positions" line the roadways here.

The Baskin-Robbins ice cream shop at Wilshire Plaza is open on a restricted schedule because of a lack of employees. Of eight from before the storm, only two have returned.

"I have signs up here and there, but I don't have enough people to work yet," said owner Katherine Roberts. Asked how much she lost during the weeks when she was closed, she said she hadn't calculated it: "I don't want to face that reality yet."

The lack of people may be partly a chicken-and-egg phenomenon, Hewings said.

"The people don't come back because the businesses aren't there, and the businesses don't come back because the people aren't there," he said.

Reopening business in New Orleans is expected to be even more difficult because of added delays, which promise to continue. High tides and winds threatened renewed flooding in the storm-ravaged city, the U.S. Army Corps of Engineers said Monday.

William H. Frey, a demographer at the Brookings Institution who studies migration, sees the long-term prospects of the population balanced between two factors. On the one hand, the region has not been growing rapidly.

"It's kind of the Rust Belt of the South," he said. "It hasn't been alluring to workers."

On the other hand, he said, natives of the state appear to have some devotion to it. No state counted more natives as a percentage of total population, he noted.

"Few other areas have a greater social attachment and sense of rootedness than New Orleans," Frey said.

Indeed, many at Harahan appear to have that same devotion. Sharon Siemssen noted that she is teaching the children of some former students.

"People just don't leave," she said. "But it's sad. Maybe this time people'll have to go."

Magan Franklin, whose house was flooded, is consoled by Derrius Richardson at Harahan Elementary School. In a science class at Harahan Elementary School, Zachary Orlando and Savannah Este look at a map showing the pupils' evacuation destinations.