The development of high-technology and services firms in Northern Virginia is shifting that area from bedroom community to an important employment center.

Many Northern Virginians still trek to Washington for jobs, but recent reports say Virginia is developing an urban structure of its own, notably in Tysons Corner. Studies over the years have shown that many jobs will be created in the suburbs, to the chagrin of urban centers such as the District of Columbia.

"Although many Northern Virginiaians commute to jobs in the District of Columbia and the Maryland suburbs, the Virginia portion of the metropolitan area is also the location of many jobs," said a report by the University of Virginia's Tayloe Murphy Institute.

No longer is the tobacco business a major occupation of the state, but services, government employment and retail trade are, according to two recent reports.

Northern Virginia makes up 34 percent of the metropolitan area and supplies about 30 percent of the jobs. That area's average earnings per worker of $14,477 exceeds the national average by 12 percent and the state average by 22 percent. Disposable income for Northern Virginians was 29 percent of the state total in 1978, the latest figures available.

Total employment increased in Northern Virginia at an average annual rate of 3 percent between 1973 and 1978 compared with a 1.9 percent rate for the nation, the report said. The largest sector of employment growth in Northern Virginia in 1978 was services, followed by the federal government and retail trade.

Services, which employed 116,475 in 1978, includes computer and data-processing services, research and developments laboratories, management and public relations firms and medical and health services. Average earnings per service employe were $15,070.

But while manufacturing's share of employments is dwindling, the average Northern Virginia worker in that sector earned $17,903, mainly in the food products, printing, publishing, electronics and transportation-equipment industries, and it still composes the singl most important segment of the state economy.

"At the national level, manufacturing continued as the largest sector through 1979," said a report published by the state's Division of Industrial Development. "However, in the U.S., as in Virginia, the long-term trend is a decline in manufacturing's relative share. Employment has increased steadily in manufacturing except for slippage in recession years, but increases in other sectors have been proportionately greater."

This trend is not surprising. The nation has shifted some of its resources from base industries, such as steel and automobiles, which thrived during the previous few decades, to high technology and services. Many of the base industries have been taken over and efficiently run by emerging less-developed nations, while the more developed one such as the the United States haven't invested much in new plant and equipment.

The tide has changed somewhat recently, however, in the steel, automobile and textile industries. But analysts of those industries maintain that they never will be as big as they once were. Employment in those areas continues to decline.

Although Virginia isn't big in steel an autos, its manufacturing specialties -- notably chemicals, lumber and leather -- have been losing employment during the last 24 years, the report said. Absolute gains were in electrical and electronic equipment, transportation equipment, food products, apparel, and printing and publishing.

Those trends parallel the national picture in manufacturing employment except in the chemical industry, which gained, and food products, which declined.

Wages, however, haven't kept pace very well in the "right-to-work" state. Virginia's average hourly earnings for manufacturing production workers in 1979 was $5.58, or 83 percent of the national average of $6.69.