Freelance journalist Maggie Messit was taking her morning jog through central Washington DC on September 11, 2001 when American Airlines flight 77 plunged into the nearby Pentagon. She remembers recoiling in horror as the plane hit the military complex and a towering plume of smoke and debris shot up overhead. But when the dust had settled literally, the 24-year-old took stock of her life. Fresh out of college, writing was her dream job, something she had always aspired to growing up in Chicago. But now she felt drawn to working more with people. “I had a rude awakening,” she says. “I realised that money wasn’t important. I just wanted to do something important - help people and go to a place that really needed me.”

Teaching fitted the bill. With a newfound sense of vocation, she sold all the belongings that wouldn’t fit into her Volkswagen Jetta and drove across the continent to California to take up a trainee position in a San Francisco school.

It’s pretty hectic juggling the demands of teaching ethnically diverse, inner-city youngsters with evening classes at a local teacher training college to become fully qualified. But Messit doesn’t regret her decision for a moment.“It’s a wonderful population of students that need extra help,” she says.

Messit is not alone in having a change of heart. Just down the corridor from her at Visitacion Valley Middle School, another new recruit has traded the plush environs of a lucrative investment banking career on Wall Street for the bottom rung of the teaching ladder. Winston Little fled the tumbling bodies and masonry of the World Trade Center, vowing to forsake the corporate life for his first love - teaching.

Obviously, these are extreme examples. But September 11 soul-searching is credited with helping stoke a recruitment boom across schools in the United States. “Anytime you have a crisis like that it makes you reassess your values,” suggests Ellen Moir, executive director of the new teacher project at the University of California, Santa Cruz. “Perhaps that kind of shocking experience creates a sense of how fragile life is.”

At America’s largest teacher training institution in Columbia University, just down the road from Ground Zero in New York, this year’s intake was up 10 per cent on 2001. Personal statements on application forms reveal that “people are looking at their priorities again and deciding to make major life changes,” says Christine Souders, Columbia’s interim executive director of enrolment services.

Meanwhile, applications for Teach for America, which places new graduates in deprived schools for two-year teaching stints, rose 65 per cent in 2002 compared with the year before; and 2001 - in the immediate aftermath of September 11 - had represented a three-fold increase on 2000. Staff are sifting 14,000 applications for 1,700 placements.

But an altruistic impulse towards public service is only part of the story.

The most important reason for the resurgent interest in teaching is the full-blown recession gripping the US economy. Many of the mid-career defectors to teaching are economic refugees from decimated corporate ranks.

New York’s annual programme to retrain people mid-career has fielded some 10,000 applications for 1,200 places. Similar schemes in Washington and Kansas have also been inundated.

At Columbia, Ms Souders reports that most career-changers are from fields hardest hit by the economic downturn, such as financial services and the airline industry. In Florida, Ava Byrne, chief of the state’s bureau of educational recruitment and professional development, notes an increase in applications from people “displaced from the technology sector”. This is part of a longstanding trend of interest in teaching running counter to economic cycles, observes veteran teacher recruiter, Thomas Jennings, associate dean for teacher education at Columbia’s Teachers College. The relative job security of teaching gains appeal when higher-paid opportunities elsewhere become limited, he says.

However, it’s not just a supply-side phenomenon. Education authorities are stepping up their efforts to make teaching more appealing. Generous wage hikes eased New York’s chronic staff shortages at a stroke this summer, while signing and relocation bonuses are other financial carrots.

Meanwhile, the authorities are becoming more sophisticated and aggressive at recruiting. Florida schools are about to mount a national advertising campaign selling a “sun, surf and teach” lifestyle to prospective recruits.

They have also made it easier for people without traditional qualifications to join the profession. In Los Angeles, school recruiters actively court candidates from non-education backgrounds under a New Teacher Project.

“We are going after high-achieving individuals who, for the most part, have had a change of heart,” says Deborah Hirsch, chief human resources officer for the city’s schools. “The vast majority of our children are in poverty and can really benefit from these people.”

New entrants are put through their paces on a six-week intensive induction course to “bring them into a realm of understanding about how to manage the classroom, create lesson plans and understand the cultural demands of teaching in a multi-ethnic urban setting”, she says. They then take their places in the classroom as trainee teachers, doing coursework over the next one to three years to gain a full teaching credential. Recent recruits include engineers, lawyers, nurses, social workers, even the chief executive of a fast-food chain, says Hirsch, herself a retired Navy captain.

The resurgent interest in teaching is timely. An estimated 2.2 million recruits are needed to plug the hole created when half the workforce retires over the next decade. At the same time, the pupil population is expected to swell by another 2 million to 54 million by 2008.

The problem is though, it’s like filling a leaky vessel with water.

Morale-sapping working conditions plus a tendency to farm new recruits out to the most demanding posts in America’s neediest schools have contrived to create a staggering staff attrition rate. One-in-five new US recruits quits within five years; in many urban schools, newcomer attrition runs as high as 50 per cent.

Florida is cultivating a cadre of experienced teachers to mentor rookies and reduce the drop-out rate. Without such redoubled retention efforts, the benefits of today’s recruitment boom will be short-lived.