Investment banker John Farrell, waiting for the morning train to Manhattan, pondered the question for a moment and then said, "No, I don't think I know anyone who's unemployed."

That's not surprising. As other cities suffer the impact of economic hard times, Stamford is booming.

Located in the southwestern corner of Connecticut, 40 miles from Manhattan, Stamford has boasted the lowest reported unemployment rate of any metropolitan area in the country for the past three months. The U.S. Labor Department reported last week that Stamford's unemployment rate was a scant 3.5 percent in June, well below the average that economists figure as full employment, when people routinely changing jobs are taken into account.

"We are the envy of every city our size in the country," said Edith Sherman, chairman of the Stamford Urban Redevelopment Commission.

As measured by the Labor Department, Stamford, with a total population of 198,000, also includes Greenwich, Darien and New Canaan, some of the wealthiest communities in America. They are storybook towns straight out of the Preppy Handbook, where tanned matrons shopping in tennis dresses say they haven't had to pinch a single penny, where the manager of a plush boutique selling $580 designer knit suits says that none of his customers has started to scrutinize price tags, where real estate listings start at $100,000 and soar into the millions.

"It's an enclave unto itself," said one resident.

In New Canaan, where the unemployment rate is 1.7 percent, social service director Antonette Casciari said no one is on the town welfare rolls due to lack of jobs. "A few weeks ago I had one young man, but he was on for a few weeks and found himself a job at a bank," Casciari said.

The reason Stamford is bustling is simple. Over the past decade, it has been transformed from a bedroom community with a decaying manufacturing base to a white-collar corporate center where more people commute in to work each day than go out.

"Stamford is a nice little New England town but close enough to New York to live in," said Gladys Cohen, whose family has operated a men's clothing store in downtown Stamford for the last 100 years.

Stamford and Greenwich have been able to attract the headquarters of 17 Fortune 500 companies, up from just one 10 years ago. Corporate headquarters in the area, set back on carefully landscaped suburban grounds or placed conveniently along Interstate 95, include Xerox, General Telephone & Electronics, United Parcel Service, Singer, American Can, and Continental Group.

As corporations fled the crime and crowds of New York, other jobs followed. "Once the white-collar business comes in, that attracts services: law offices, and advertising agencies, and cleaning services, and food services," said Pobie Johnston, vice president of the Southwestern Area Commerce and Industry Association. Although it lost 1,000 manufacturing jobs, Stamford had a net gain of 13,300 positions between 1970 and 1980.

And while slumping profits may have induced some companies to slash manufacturing and cut production workers elsewhere, corporate employes are generally the last to feel the sting.

"Your headquarters is not like a factory," Johnston said. "They still have to do planning, they still have to get legal advice. You're not going to see the kind of layoffs you have in manufacturing."

At Champion International, for instance, where profits plummeted 84 percent during the first half of 1982, not a single position has been cut, although the impact has been felt in everything from freezes of salaries, hiring and overtime to the disappearance of fresh flowers on tables in the company cafeteria.

"This is not Camelot," said Robert N. Rich, president of the F.D. Rich Co., which has overseen the redevelopment of 130 acres of downtown Stamford. "We're not unaffected by what's happening in the rest of the world. But there's so much new happening it hasn't really hit us."

Evidence of the boom abounds. A mall that will eventually contain 130 stores and create 2,500 jobs opened in downtown Stamford in February, with Brooks Brothers, Laura Ashley, F.A.O. Schwartz, and "the most upscale Macy's you've ever seen," according to Rich.

Bloomingdale's has just completed a $10 million renovation. Singer opened a new downtown headquarters last year. A 10-story office building will top the Saks Fifth Avenue that is to open at the mall in February, the sixth office building in a downtown complex that already contains 620,000 square feet of office space.

A 305-room Marriott hotel, one of the jewels of the original redevelopment, is planning a 195-room addition. A Holiday Inn is under construction, and Sheraton has announced building plans.

Pitney Bowes, the postal meter maker that is one of the few large manufacturers left in Stamford, has started building a new corporate headquarters to help revitalize the declining South End. A new railroad station is in the works. Champion, Pitney Bowes and F.D. Rich have bought a decaying downtown cinema and are hoping to turn it into a $3 million Stamford Center for the Arts. The city just opened a $7 million library addition, wrapping a modernistic white building around the fluted columns and brick of the original facade.

"The demographics are excellent," said Saks Vice Chairman Frank J. Armsworthy with a grin as he explained his company's decision to come to Stamford. The average household income in Stamford doubled between 1970 and 1980, from $14,994 to $29,365. The figures for the surrounding towns are even higher: $41,419 in Greenwich; $53,275 in New Canaan; $58,987 in Darien.

Those statistics are another reason the unemployment rate looks so low. Unemployment is measured by residence rather than place of work, and Stamford housing is simply out of the price range of many of those who would be vulnerable to manufacturing cutbacks. With the average price of a house $180,000 last year, "you can't afford to be unemployed in Stamford," said Harriet Cassidy, director of the unemployment office.

There are other strains in Stamford that the unemployment numbers hide. The city welfare agency reports a record caseload, 380 cases this July compared to 65 a year ago. With a growing number of Cuban and Puerto Rican immigrants coming to town, an emergency shelter at St. Luke's Church is "full almost all the time," said casework supervisor Robert Mendela.

"Most of our people never show up on unemployment because they've never had a job for long enough to collect unemployment," said caseworker Christine Varner. And while rooming houses where the poor used to live were bulldozed to make room for the mall, most of the jobs it has to offer aren't open to the hardcore poor. "Macy's isn't interested in our people to sell their clothes," she said.

A mere half-mile from Champion's new aluminum headquarters, complete with a branch of the Whitney Museum of American Art on the ground floor, are depressed areas that rival 14th Street NW in Washington. "I'm willing to work but I can't no way find a job," said Abraham Williams, who was hanging out by Goodfriend's Pool Room and Shoe Shine on West Main Street.

"You see all those help-wanted ads in the newspaper?" asked Williams. "You follow them up and see where it leads you. Nothing. It's a dead end."

As elsewhere, Stamford's black community, 17 percent of the population, has been much harder hit by unemployment than whites, with minorities accounting for half the 4,500 reported unemployed for June.

A visit to the unemployment line also found that even skilled workers aren't sailing their way into jobs.

J.W. Syrokwash, for instance, was bringing home $50,000 a year working weekends and overtime on the Bloomingdale's renovation as a union carpenter. Despite all the construction, "there's not enough jobs to go around," said Syrokwash, who has been collecting $156 a week in unemployment for the past three months. "This is the first time in 20 years it's taken me this long to find work."

Even those with jobs are feeling the economic pinch. "I make enough to cover the bills, but that's not enough to do anything else," said Lynn Brown, who works in the international quotation department at Omega Engineering but was at Macy's personnel office last week looking for a second job.

Still, whatever ripple effects from the recession that Stamford has felt are mild compared to the shock waves that have hit other cities. And Stamford Mayor Louis A. Clapes doesn't expect that to change.

"The quality of life is good and we're continually improving," he said. "I think Stamford's future looks brighter than ever." CAPTION: Picture, Ferguson Public Library in Stamford, Conn., recently opened a $7 million addition, the modernistic white building at left. Plans for a $3 million art center also are under way. Stamford Advocate; Map, no caption, By Dave Cook -- The Washington Post