Jul. 23--Sometimes the jobs moved to Arizona. Sometimes they moved to China. And sometimes, thanks to Silicon Valley's tech prowess and prolific workforce, the jobs just went up in a puff of smoke.

"It was scary," said Kiranjit Banwait, let go in 2004 as an assembly-plant machine operator for a computer maker.

"They closed our plant in San Jose and outsourced like every other company to Singapore and Mexico. Everyone was getting laid off in manufacturing so there was no point in looking there anymore. The jobs had just disappeared."

Along with keen innovation, intoxicating sunshine and world-class universities, one of the Bay Area's trademarks has been its steady erosion of manufacturing jobs. Decades of workplace detritus litter the region, from shipbuilding to aerospace to computer chips.

And that trend could accelerate with the seemingly imminent closure of Fremont's NUMMI auto plant, threatening nearly 5,000 workers with the sort of extinction pink-slip veterans like Banwait have known first-hand.

"Manufacturing in Silicon Valley has always been evolving," says Josh Williams, a research consultant working for the Joint Venture: Silicon Valley Network. "In the late '90s, it was all about fab(rication) plants building new computers, hardware and printers. A lot of those jobs are gone now, but they provided good strong middle-wage jobs, and in many ways the basis of our economy is finding jobs that are sustainable."

From a peak

in the San Jose metropolitan area of about 264,000 manufacturing jobs in 2000, to about 165,000 in 2008, the long slide has sent thousands of job-seekers packing for other states and left countless others scrambling to find replacement work.

But like Banwait, who retooled his skills and became a medical assistant, the tumult has also pushed thousands to re-evaluate their careers and broach new fields. That, in turn, has helped burnish the Bay Area's reputation as an economic contortionist, constantly twisting its employment profile while perched at tech's cutting edge.

In fact, the total number of jobs in the seven-county region, according to state figures, has risen from about 2.66 million in 1990 to nearly 3 million last year.

That agility "is in the DNA of this place," says Bruce Kern, executive director of the East Bay Economic Development Alliance, which has been hoping to nudge NUMMI into its next smart-car incarnation.