One of the more encouraging developments in the District's economy has gone virtually unnoticed in a recent spate of announcements connoting the continuation of an economic boom in metropolitan Washington.

Unemployment in the District, which was well above 12 percent three years ago, was down to 7.6 percent in January, falling to its lowest level in 10 years for that month. The previous low for the month of January was in 1975, when the jobless rate was 6.6 percent.

Also, the 7.6 percent January jobless rate is the lowest in the District since the period before the onset of the recession in 1980.

The January unemployment rate was reported in March and is the latest figure officially reported by the D.C. government.

The latest jobless figure and, indeed, the unemployment rates reported for the District toward the end of 1985 seem to confirm the existence of a trend that labor-market experts very cautiously cited last winter.

Continuing a string of three consecutive years in which there was an increase in resident employment growth, total joblessness in the District declined from 29,000 in 1984 to 27,000 in 1985.

The District has "recaptured" most of the employment that it lost in the early part of the decade, according to an official in the D.C. Department of Employment Services. "The underlying factors show the trend in unemployment in the District is down," the DES official remarked.

Indeed, the DES forecasts more of the same for the remainder of 1986. "Given the modest forecasts of economic growth for the Metro Area in 1986, the District's employment situation should continue to show modest improvements during the year," the DES noted in its latest report on the status of the area's labor market.

Aside from the obvious implications for the District's economy, the interesting thing about the improvement in the employment picture is that no one is prepared to say unequivocally what factors are most responsible.

"I think it's the general growth of the area that's absorbing some of our unemployed," suggested Richard Groner, director of the division of labor market information and analysis at the DES.

No doubt, Groner is correct. If that is the case, then it proves what a good many astute observers of the local economy have been saying for some time: The nine jurisdictions that comprise metropolitan Washington are inextricably tied to a single regional economy, and major economic changes in one or more of those jurisdictions are likely to have an impact on all segments.

While there is obvious growth in the area's economy, the District has benefited from a relatively strong private sector that continues to produce more jobs than the shrinking public sector.

Whatever the reasons -- growth in the region's economy, expansion of the District's private sector, or serendipity -- the emerging picture appears to be better at this stage than the December forecast of a slight decline in the District's jobless rate in the first half of 1986.

One D.C. official suggested that Mayor Marion Barry's initiative in calling for area officials to work cooperatively in identifying employment opportunities for the jobless might have contributed to the decline in unemployment among District residents. It's far too early to assess the results of the mayor's efforts, but it's safe to say that the program has had some positive returns.

Barry has held at least three meetings with employers and elected officials in suburban areas since announcing his seven-point plan last summer to match unemployed D.C. residents with jobs in the suburbs, where labor shortages had become a problem. Although some area officials appeared less than enthusiastic initially, the proposal appears to be gaining acceptance.

That is also an encouraging sign. Moreover, it is an indication that area officials are prepared to accept one of the more compelling conclusions in a study that was done three years ago for the Greater Washington Research Center.

"How [the region's] economy evolves will be affected by the accumulated actions of individual businessmen and public officials," concluded the study's authors. "The product of their actions will affect the region's residents -- their employment and their income levels."

That, in the final analysis, may be the underlying reason for the brighter employment picture in the District.

Tuesday's column on the legal battle over Techworld incorrectly described a concession that developer Giuseppe Cecchi offered to make in exchange for support from preservation groups. The amount Cecchi proposed to invest in landscaping Eighth Street NW is $100,000.