A peek at US portrait drawn by '80 census

It took a long time to develop them, but the first snapshots of the US population are finally emerging from the 1980 census.

Bruce Chapman, head of the Census Bureau, revealed some of the major changes between 1970 and 1980:

* The US labor force increased 30.6 percent to 104.5 million. Of that, the number of male workers has increased 21 percent to 59.9 million; women, 46 percent to 44.6 million.

* The percentage of persons 25 years and older who are high school graduates jumped from 52.3 percent to 66.3 percent.

* This is the first census in history to show that more than half the residents 25 years and older of every state have completed at least four years of high school.

* Median household income in 1979, based on provisional samples, rose to $16, 830. This looks like an enormous jump of 98.3 percent over the 1970 figure, but most was due to inflation.

''After adjustment for increases in consumer prices,'' the report says, ''there was no significant change in real median household income over this period.'' Households are defined as all the persons who occupy a housing unit. While family households increased 15.7 percent in the decade, nonfamily households (persons living alone or with nonrelatives only) went up 71.9 percent.

Individual income purchasing power advanced slightly in an era of price-doubling inflation: real per capita income in 1979 was $7,313, an increase of more than 18 percent.

The report compares figures geographically and by population groups. Alaska median household income was highest at $25,109; Arkansas lowest, at $12,156.

Among population subgroups the median income for white families was $20,840, compared with $12,618 for blacks.

Sociologists will debate these early preliminary samplings.

For example, one random snapshot shows that the majority of workers in the US -- 65 percent -- drive to work. Of that number, only about 20 percent are members of car pools, despite government efforts to promote gasoline conservation. Six percent use some form of public transportation (buses, streetcars, subways, railroads, and taxis.) The Census Bureau notes that about as many Americans walk to work as use public transportation.

The first census samplings were revealed in a jam-packed conference room in the Commerce Department while a 21-gun salute outside proclaimed the arrival of Queen Beatrix of The Netherlands at the White House.

Census chief Chapman explained that the preliminary figures released here are provisional and based on a sample of a sample: a survey of 3.5 million people. This amounts to 1.5 percent of the total national population, whereas the final census figures will be based on about 20 percent of the nation's households.

The same 10-year inflation that shows that median household income has doubled shows housing costs for renters up 125 percent. These are the first detailed figures for the 50 states, the District of Columbia, and the 38 biggest ''standard Metropolitan statistical areas,'' i.e. cities. The figures are a sampling of the detailed long forms filled out April 1, 1980, by 20 percent of the nation's residents, giving 1979 figures. Social, economic, and private commercial campaigns for the next 10 years will be based on such figures.