Last summer, Fairfax County contractor Bob Murphy couldn't find nearly enough skilled labor. Frustrated, he decided to accept only custom jobs. It would be easier, he reasoned, to recruit talented carpenters for such prized work.

Murphy still needs 10 carpenters. Lacking sufficient help, he has had to slash his workload by one-third. "I'm turning down four or five jobs a week," he said.

A year ago, suburban Washington employers were experiencing the most severe labor shortage in recent memory. In Montgomery County, for example, the unemployment rate was 2.5 percent, close to what many economists consider full employment. In the District, however, the rate was 8.4 percent, and Mayor Marion Barry launched an ambitious program to connect city residents with jobs.

Barry's program found work for more than 2,000 D.C. residents, and with the help of a revitalized District economy the unemployment rate in the city now stands at 6.5 percent, its lowest in 12 years.

In the suburbs, however, the lack of workers is even more acute than before, reaffirming that the Washington area, whose economy once was dominated by the central city, is sprouting economic centers around the Capital Beltway -- each a magnet for job seekers.

What once may have seemed a simple solution to the suburban job glut -- tapping city workers for reverse commuting -- does not go far enough.

Instead, the city is approaching its own level of virtual full employment, experts say, with only the hard-core jobless left behind, and the suburbs are scrambling even harder for the manpower to handle their growth.

Fairfax County has become an economic core of its own, drawing laborers not only from such counties as Prince William and Loudoun, which have become virtual suburbs of Fairfax, but also from as far away as North Carolina and Pennsylvania.

"For better or for worse, America's job places are decentralizing at a rate that has no precedent in history," said George Sternlieb, director of the Center for Urban Research at Rutgers University. "The real band of development in major metropolitan America is 30 to 50 miles out. This holds true in Chicago as much as it does in New York and, certainly, in Washington."

It is not just skilled workers who are in short supply in the Washington suburbs. Grocery store baggers, record store clerks and department store cashiers are also at a premium.

"The situation has gotten progressively worse," said Tony Ahuja, technical services director at the 1,250-member Northern Virginia Builders Association, echoing the views of many of his suburban colleagues.

Increasingly, employers are being forced to lure prospective workers with such incentives as bonuses for workers who recruit friends. At 7-Eleven stores, an aggressive media campaign is aimed not at selling hot dogs or promoting videotape rentals but at attracting clerks.

One Arlington County employer is so thrilled to have discovered a new source of skilled cabinetmakers in a far-flung city, west of the Mississippi River, that he will not mention its name lest his competitors find it.

In Northern Virginia, where the April unemployment rate was 2.9 percent, officials said there was no way of determining precisely how many jobs are going begging. But they agreed with employers that the shortage of workers is severe.

About 48,000 jobs were created in Northern Virginia between April 1985 and April 1986, more than twice the number created in the District, according to the Virginia Employment Commission.

During the last year, Northern Virginia employers registered 18,242 job openings with the Virginia Employment Commission, including 4,162 clerical positions, 3,309 sales jobs and 3,219 service jobs. The commission was able to fill 6,414 of those openings, according to Bill Pritchett of the job services division.

Three thousand job openings for skilled and unskilled workers are listed with the commission's Northern Virginia office, but that represents only about a quarter of the available jobs, said Charles Greene, assistant office manager. He based his estimate on the "accepted standard" belief among employment officials nationwide that as many as 75 percent of the empty jobs are not listed with them.

In suburban Montgomery County, where the April unemployment rate was 2.1 percent, 1,867 jobs were listed with the Maryland Department of Employment and Training at the end of June, according to spokesman Curtis M. Kane.

According to the May report of the U.S. Bureau of Labor Statistics, the metropolitan area, with an unemployment rate of 3.1 percent, had about the lowest rate in the country, ranking 230th of 235.

There are several reasons that Washington area employers have not been successful at recruiting from the suburbs the workers they need to fill their jobs, particularly those paying entry-level wages.

"The big issue in Washington, or Manhattan, or, for that matter, definitely in Chicago, is that we now have the 'baby-bust' generation on us," said Sternlieb. Fewer people, he said, are entering the work force for the first time.

It is particularly tough in places such as Fairfax County, where more than 87 percent of high school graduates go on to higher education and many do not seek summer jobs -- students being a traditional source of low-income labor.

In addition, there are few blue-collar workers in Fairfax; 77 percent of the working residents are in white-collar jobs, according to the 1980 census.

Nor can employers rely on the old reserve pool of homebound suburban women; most women who want to work already have jobs, said George Grier of the Grier Partnership, a Bethesda-based demographic and economic consulting firm.

The lack of public transportation in many sections of sprawling Fairfax County compounds the problem; the jobs are not always accessible to commuters without cars.

"All of us out here in Northern Virginia right now are probably short of help," said contractor William A. Hazel, who estimates that he needs as many as 60 workers to round out his 1,200-member work force.

A partial solution is to recruit the District's jobless, because Washington, like many metropolitan areas, experiences a discrepancy between city and suburban unemployment rates.

Rutgers' Sternlieb said today's suburban labor shortages present a "window of opportunity to bring minority groups from the center city aboard the economic train." He questioned whether that will happen, and also "whether there's anybody employable out there."

He said it has proved to be "very, very sticky nationally" to bring inner-city unemployment rates much below 5 percent. "These are people who, in many cases, have not just fallen off the economic train; they never got on it." He, and others, spoke of the need for programs to help these people develop good work habits.

"The one thing we do know," Sternlieb said, "is that black unemployment has been remarkably resistant to the unprecedented job surge in America."

Some officials, experts and District residents cited travel difficulties and low-paying, entry-level jobs as deterrents to bringing city residents to the suburban work force.

Increasingly, frustrated suburban employers said they are turning to distant sources of labor.

"It's easier to go to West Virginia to get employes than it is to go to the District," said Ken Cleaveland, executive director of the Virginia chapter of Associated Builders and Contractors Inc. "It's easier to get those people from 200 miles away than it is from 20 miles away."

At Arlington Woodworking & Lumber, a company official said the difficulties in finding workers close to home led him to advertise in a western city.

"We put the ad in a paper 1,500 miles away and, my God, there were people on our doorstep," he said. "One fellow told us not to hire anyone else, he was getting in his car that day. Sure enough, he showed up on Monday morning, ready to go."

At Hazel's construction company, former coal miners from Pennsylvania and West Virginia are prized applicants because of their heavy-equipment skills and eager attitudes. "Those country boys have had to work ever since they've been born," said Smith, the general superintendent.

Nearly 75 percent of his more than 1,000 employes live outside the metropolitan area. Of those, half are from West Virginia. Others come from Pennsylvania and rural Virginia. Many commute each day; some camp in their trucks at the company parking lot, where there are showers and toilet facilities.

That employers are importing labor is not unique to Washington, said John Bregger, chief of the employment and unemployment analysis division for the U.S. Bureau of Labor Statistics.

But some believe that these workers cannot be considered "imports" any longer. As Washington has expanded, so has its concept of exurbia. Instead of living near the Beltway and commuting into the District, an increasing number of people are settling farther out and working in the suburbs.

John McClain, director of metropolitan development for the Metropolitan Washington Council of Governments, suggested that those who live more than 1 1/2 hours away by car may be commuting here temporarily until they can either find work back home or move to this area.

Sternlieb said he believes that most will remain and that they should be considered part of the region's dependable labor force. Nobody, he said, wants to return to a nonexistent job in the West Virginia coal mines.

An increasing number of employers are turning to professional search firms for help in finding construction engineers and project estimators.

Walter Davis, president of Davis Associates Management Consultants, said business has improved "considerably" in the last year. But because so many people are vying for the same construction executive candidates, he finds it increasingly difficult to find suitable applicants.

Part of the answer, at least for entry-level construction workers, is to offer more training, said Cleaveland. He estimated that only 20 percent of Northern Virginia construction companies are actively participating in training programs.

"It means that 80 percent are out there stealing the ones that are trained," Cleaveland said. "There's quite a bidding war. A good skilled journeyman or mechanic can pretty much write his own ticket."