The black population of the District of Columbia has remained relatively stable since 1970 while the number of white households in the city appears to be on the increase, according to a census Washington Center for Metropolitan Studies.

The findings of the census update, conducted in late 1974, are less than conclusive with regard to a permanent growth in the District's white population, George W. Grier, who prepared the census update, said yesterday.

But, after years of decline, the census update recorded a sharp increase in the number of white families who moved to the city during 1974, a trend that Grier said seems to be continuing. For the first time in decades, the number of whites moving into the District may eceeed those who die or leave the city for the suburbs.

"If we took another survey today," Grier said, "I think we would see a great acceleration of (the) in-movement" first detected in 1974.

Like several other cities across the country, Washington is viewed as an increasingly attractive place to live by single persons and young, upper income childless couples of both races, according to a housing preference survey conducted last year by the center and also released this week.

This survey found that about a quarter of the 90,000 upper income families already living in the Washington metropolitan area who plan to move in the near future expressed a strong preference for the cultural and entertainment amenities available in the District.

If housing were available and if in-town neighborhoods were considered safe, the District could attract approximately 15,000 to 20,000 new households a year just from within the metropolitan area, the survey found.

Both the census update and the housing preference survey tend to confirm what city developers, speculators, planners and real estate brokers already know: houses and apartments almost anywhere west of the Anacostia River can be sold or rented almost as fast as they become available.

Neighborhoods such as Adams-Morgan, Mount Pleasant, Dupont Circle, Logan Circle, far-out Capitol Hill and even Shaw have experienced an influx of middle and upper-middle income families in recent years as houses are renovated by developers and then sold, offer for prices in excess of $50,000 and sometimes at prices approaching $100,000.

In some cases, young singles or childless couples buy renovated houses and refurbish them over a period of time all by themselves. According to real estate brokers who specialize in these inner-city areas, young blacks appear to be buying in large numbers although the whites who buy are more visible in what were, until recently, all-black neighborhoods.

J. Gerald Lustine, whose real estate firm is most active in neighborhoods east of 16th Street NW, said recently that black families seem most interested in houses that sell for under $40,000.

If a black family can afford to pay $50,000, Lustine said, more often than not it will opt for the suburbs.

"They're not interested in buying the same kind of house they rented for so mnay years," even if it is renovated, Lustine said.

The Washington Center for Metropolitan Studies census update confirms Lustine's general observation. Approximately 20,000 black families who lived in the District in 1970 were living in the suburbs in 1974. This outmigration might explain why the number of black housholds in the city in 1974 was only 3,000 greater than the number living here in 1970.

In all, the census update found that 119,000 single persons or families living in the city in 1974 had moved at least once since 1970. About 68,000 (57 per cent) of the 119,000 simply moved from one address to another inside the District during the 4 1/2-year period.

Approximately 41,200 of the households living in the city in 1974 who had moved since 1970 cam e from outside District. Of these newcomers, 34,200 came from outside the Washington metropolitan area. Another 7,000 newcomers to the city moved in from the Maryland and Virginia suburbs.

Of the 41,200 newcomers, 26,100 were white (63 per cent) while 13,500 were black (33 per cent) and 1,600 (4 per cent) were of other races or failed to respond to the census question pertaining to their race.

Another 10,000 heads of household living in the city in 1974 had moved since 1970 but the census was unable to determine whether they had lived inside or outside the city when the federal census was taken in 1970.

The most striking statistic uncovered by the census update is that the District experienced a great influx of newcomers during 1974. More than 19,000 of the 41,200 new households residing in Washington at the time of the update had moved to the city during 1974.

Most of these 19,000 newcomers were white, according to the census update. However, the apparently unusual influx of newcomers could be explained in at least two ways, Grier said.

On the one hand, the District's population could be so transient that approximately 20,000 newcomers could come and go during any 12-month peiod - accounting for what appears to be an unusual influx during 1974 but what, on closer examination, could be a normal count of the city's transient population.

On the other hand, Grier said, the influx could, at least in part, reflect a real increase in the number of new households moving into the city on a more permanent basis. Grier said he believes this latter explanation is probably the case.

The District was experiencing a real inflow of new residents in 1974 (above and beyond the normal transient inflow), Grier said, and the late 1974 census update caught this trend.

The census update also found that:

Most newcomers to the city located in "central locations undergoing private rehabilitation, in the renewal areas or in high prestige areas on the west side of the city,"

Nearly half of the newcomers to the District between 1970 and 1974 were single and held college degrees;

Two-thirds of the newcomers were under 35 years old;

The overwheling majority of the newcomers rented houses or apartments rather than buying them;

Two-thirds of the newcomers to the District between 1970 and 1974 were white an increase over the percentage of newcomers to the city between 1965 and 1970 who were white.