Whites and blacks in Prince George's County are more alike in income and education than in any other part of the metropolitan area, while the gap between the races is widest in the District of Columbia, according to new data from the 1980 census.

In Prince George's, the census figures show, both races are mostly middle class. Whites had higher incomes and more years of education, but the differences narrowed slightly during the 1970s as blacks swelled from 14 to 37 percent of the county's population.

In Washington, the split widened during the decade between mostly upper-income whites and mostly lower-income blacks, as many middle-class black families left the city. The District's population of both races declined sharply during the decade though the proportion of blacks remained at about 70 percent.

The new report, issued yesterday by the Metropolitan Washington Council of Governments, shows that the median family income for Prince George's blacks was $23,140 in 1979, as gathered by the 1980 census -- about 85 percent of the $27,360 median for Prince George's whites.

In Washington the black median family income was $16,410 in 1979, just 46 percent of the $35,825 median family income for whites.

Washington's whites had the highest income of any whites in the area, surpassing those of Montgomery and Fairfax counties, both of which had higher incomes than D.C. whites 10 years earlier.

Meanwhile, the new data show that Washington's blacks have the second lowest median family income in the area, above only those in Alexandria. In the 1970 census, D.C. black families had higher incomes than those in five of the eight principal suburbs.

Prince George's blacks, on the other hand, have the second highest income of any black group in the area, just $480 below those in Montgomery County.

Prince George's whites have the third lowest income among the area's whites, just above Prince William County in Virginia, which has large, relatively low-income rural areas.

However, they still are far above the nationwide average for whites of $20,840.

The COG report also gives new census data that show that:

* The number of suburban commuters coming into the District to work rose during the 1970s by 75,373, a 28 percent increase. The number of suburbanites working in their own jurisdiction or another suburb increased even more -- by 214,217 or 37 percent.

* District residents in the work force declined by 8.3 percent, compared to a 15.7 percent drop in the city's population.

* Automobile ownership throughout the area surged by 47 percent, a far greater increase than the 4 percent rise in population and the 27 percent increase in those employed.

John McClain, COG's assistant director for planning, suggested that the number of automobiles soared, despite the opening of the Metro subway, because of an increase in families in which both husband and wife hold jobs in the suburbs.

* Use of public transit for commuting rose during the 1970s by about 50,000 riders a day to 240,369 in 1980, a 26 percent increase. This was in contrast to the transit losses of the 1960s. But those using cars to get to work rose by about 248,000 from 1970 to 1980, a 27 percent increase.

The proportion of all workers commuting by public transit rose just slightly from 15.3 to 15.8 percent.

* Women accounted for almost two-thirds of the 321,058 increase in area residents employed over the decade.

* The value of owner-occupied homes in the area rose by 186 percent in the 1970s, compared to the 116 percent rise in median family income.

* Overall, Montgomery continued to surpass Fairfax as the jurisdiction with the highest median family income, though Fairfax made greater gains.

* The new data on education show that about 77 percent of both white and black adults in Prince George's County have high school diplomas -- the only jurisdiction where the proportions are the same. About 23 percent of Prince George's whites have college degrees, compared to 15.6 percent of its blacks, the smallest gap in the area.

In the District, 57.5 percent of white adults have graduated from college, compared to just 12.2 percent of D.C. blacks. The proportion of District whites with college degrees is far greater than in the highest suburb, Alexandria, where it is 47.3 percent.