When the 1970s began, suburban Prince George's County was home to large numbers of white moderate-income government workers. A relatively small number of blacks lived in one corner near the District line and the Capital Beltway served as a neat boundry between black and white Prince George's.

A decade later, during which the country witnessed court-ordered busing, a huge run-up in the price of housing, a massive in-migration of blacks and an equally large out-migration of whites, Prince George's has become a biracial county that is 59 percent white and 37 percent black, according to last month's long-awaited Census Bureau figures.

Studies of the new census data and interviews with planners, politicians and real estate people shatter some common misconceptions about blacks and whites in Prince George's:

Prince George's gained nearly twice as many blacks as the District lost, putting to rest the notion that the new black residents of the county are merely those who crossed the border from the city.

The surge in black population came not just from impoverished blacks pushed over the District line into cheap apartments. In many cases, they were two-income professional and semiprofessional families buying their first or second homes.

"I suspect that the economic status of the blacks that came in is at least equal to that of the whites that left," said John McClain, assistant director for planning of the Washington Council of Governments (COG).

Blacks can no longer be considered only "inner-Beltway" dwellers; 25 percent live outside the county's psyhological meridian, compared with 39 percent of the county population as a whole.

Black leaders say they are determined to flex their newly validated political strength in crucial redistricting battles for the school board, county council and legislature that will take place during the next 12 months. In a struggle that has already begun, blacks are demanding additional seats for black representatives. Black officials now hold one of nine school board seats, three of 11 county council seats, one of the eight senate offices and two of the 24 delegate positions.

Except for a sharp increase in 1972 due to change in eligibility rules, the county welfare caseload has not burgeoned with the racial change. The total number of cases was roughly the same in 1978 as in 1972. In a 1975 study, the recipients remained equally divided between white and black.

The crime rate per 1,000 residents during the 1970s generally increased faster in Prince George's than in Montgomery or Fairfax counties. However, in certain categories, such as rape and aggravated assault, Montgomery had a faster rate of increase than Prince George's.

It was affordable housing on abundant land, the promise of good schools and the largest stock of rental housing in the metropolitan area that drew 156,000 blacks to Prince George's in the 1970s. Their number has increased from 91,000 in 1970 to 247,000 or more today.

They replaces, almost to a man and woman, 170,000 whites who left Prince George's for surrounding counties or other areas of the country, say the demographers. Lured by lower taxes in nearby counties, scared by busing and new faces in the neighborhood for Sunbelt retirements, an astonishing 43 percent of the whites who lived in Prince George's in 1970 were gone by 1980.

John McClain of COG noted that while Prince Geoge's total population grew only slightly over the decade, Charles, Calvert and Anne Arundel population combined grew by 111,762, due at least in large measure to white migration from Prince George's.

Overall, the older areas of the county, such as Bladensburg, Chillum, Riverdale and Hyattsville, lost population, while districts in the once-rural southern half of the county, such as Piscataway, Surratts and Oxon Hill, increased dramatically. In both types of areas, however, the black percentage of the population grew.

Much of the black growth has occurred in the county's large stock of moderate- to low-priced apartments, such as those that line Pennsylvania Avenue (Rte. 4) from Silver Hill Road to Donnell Drive, changing the complexion of entire areas over a few years. At the same time, however, there has been a substantial but as yet unmeasured growth in the number of black, middle-class families who own their homes.

Indeed, said McClain, some of the largest black inroads into the county have come in higher-income areas such as Ft. Washington, Tantallon, Apple Grove and Rosecroft -- all in southern Prince George's.

The turnover in houses has been good for the real estate business, according to Mike Casey, former president of the county Board of Realtors. Casey said many of the homes he sold to blacks during the '70s were bought with the proceeds from the sales of homes in District of Columbia neighborhoods such as Capitol Hill.

"At that time there was a tremendous increase in the price of housing in Washington. That had a great bearing on what happened in Prince George's County," he said.

"I saw great trends right after busing came in," Casey added. "A lot of people just didn't want that busing. If they wanted to get away from it they had to move."

The county's busing plan for racial integration, ordered by a federal court in January 1973, is given credit, or blame, as the single most important cause of the flight of whites. Paul Larkin, director of institutional research for Prince George's Community College, together with several planners and economists, began studying these trends as early as 1975.

"One of the things we had come up with then was a continuous, strong in-migration of blacks," said Larkin. "There was not a sudden influx of hundreds of thousands of blacks but there was, however, a sudden outmigration of whites -- associated, we thought, with the busing decision in 1973."

County Executive Lawrence J. Hogan, who represented the county from the Fifth congressional district in 1973, recalled telling Sylvester Vaughns, the black community activist who brought the suit that led to the busing order:

"'if you want Prince George's to become an all-black county, busing will contribute to that.'" Hogan added, "The way to solve the integration problem is not through forced busing but by integrating neighborhoods. We probably have more racially imbalanced schools now than before busing."

County Council member Sue. V. Mills, who earned her potent political name at the forefront of the busing opposition, said integration was proceeding at a "healthy rate" before busing, "and then everything exploded." As a result, her Oxon Hill neighborhood and original 12th election district political base is now 52 percent black.

"I think it was the emotional impact -- not the busing itself, the sense of instability," said Mills. "I believe that had a tremendous effect. The feeling of instability is still there," she said. "And the negative effect on the school system is still there."

Mills said the shift in Oxon Hill does not concern her as an elected official, but she notices the differences as a neighbor.

"These people are my constituents. Just because the color of the face has changed, that hasn't changed," she said. "Where I used to know everyone on my street, I don't any more. It's not a physical destruction (of the neighborhood), but you don't have the closeness," she added.

Mills said ending school busing for integration would be "the greatest shot in the arm this county could have."

But other county observers and residents said busing is only one part of a complicated picture.

School board chairman Jo Ann Bell lives in District Heights, the heart of the Spaulding election district 6. That district was home to 53,000 of the 170,000 whites who left the country. It has gained 38,000 blacks.

"Even if you didn't have forced busing you'd have some kids riding on buses," said Bell. She also noted that large numbers of children were not buses out of her neighborhood for school integration.

Bell said the shift in District Heights was so subtle that it surprised longtime neighborhood residents at last year's 4th of July parade.

"I was riding in a car and I kept hearing, 'My goodness, my goodness.' Later when I was mingling with the crowd I kept hearing, 'My goodness, I didn't know we had so many new neighbors,'" Bell remembered.

Bell, a 19-year resident, described many of the white families who left the quiet tree-lined streets of District Heights in the 1970s as having reached the end of the child-rearing cycle. They were people, she said, who had left Washington in the 1950s to buy brick houses in the new suburbs; by the 1970 their children were grown and, for the most part, independent. Rather than maintain their nearly 30-year-old homes, they went to condominiums in Chesapeake Beach or Reston, Va., reaping handsome profits from selling their houses in the process.

Younger families, she said, simply outgrew the three-bedroom houses and looked for areas where they could have more space at a convenient price and lower property taxes. Some moved to southern Prince George's, which experienced explosive growth over the decade, but many left the county for Anne Arundel, Charles and Calvert counties.

Joanne Brown, president of the county council of PTAs, also lives in the District Heights area. She gave the same description of the families who left her subdivision, but noted that purely racial considerations and the fear of crime also played a part in the change.

"Originally it was a predominantly white neighborhood, and when the blacks moved in, the whites moved out," she said. "To be honest, it was the stigma of the blacks coming into the community."

Brown said the typical black family buying into the area had two wage earners and few children, compared with the mature, one-income white families who moved out.

As for her new neighbors' care and upkeep of their property, she said, "I think they are better than the ones they replaced." On the other hand, she noted that the racial change in the schools, now 49.9 percent black, and busing have hurt the county PTA organizations she heads.

"In 1971 when it all began, we had a much higher number of participants than we have now," said Brown. It's like a slow cancer eating away," she added.

"A lot (of the new residents countywide) don't take the schools to be their own. A lot of people don't even know where their school is. In the schools that I go to, I see a lot of black parents; whether they actively participate, I can't say."

Brown's fears are the other side of the hopes that many black residents, political and community leaders hold for a new black future in Prince George's County that officially began on Friday, March 13, when the 1980 census figures were published.

"The baby's just been born and there's a lot of negative reaction. It will be very exciting if we can educate the black folks to the potential we have here," said Brown.