Another in a biweekly series of stories about the people and events that shaped Washington in the 20th century.

Suddenly that summer, everything changed. The evenings of pleasant chitchat -- a dozen or so husbands and wives lounging on lawn chairs in front of their Petworth garden apartments -- turned serious. Parents shooed the children away and lowered their voices.

White families were fleeing the neighborhood as black families moved closer. Each departure was dissected: Where were they going? How did they get the money? Who was moving in? Race was never mentioned. It didn't need to be.

"It would be `they,' " recalled Paul Wice, who was 12 years old in 1954, when the hushed conversations began. "It was understood who the `they' were: `Oh, they're coming onto Farragut Street. So-and-so is moving.' "

Thousands of white families left the nation's capital during the 1950s, buying homes in Maryland and Virginia so new they still smelled of paint. Wice's family joined the exodus in 1956, heading for Wheaton after the school year was finished. By July of the following year, the District had become a majority-black city for the first time in its history.

The black families that moved into the formerly all-white blocks were mostly middle class, yearning themselves for larger homes, better neighborhoods to raise their children. They were pioneers of a sort, facing the hostility of their new neighbors at the same time as they struggled to pay their new mortgages. They never intended to cause racial upheaval; they just wanted a nicer place to live.

The change was especially dramatic in Anacostia and a swath of neighborhoods east of Rock Creek Park.

Demographics were changing in most of the nation's biggest cities during those years. Whites were leaving, and new ones were reluctant to move in. It was not simply prejudice that drove the flight; in many cases, it was a murky mix of bias, peer pressure and the fear, encouraged by real estate speculators, that the value of houses would plummet when blacks moved in nearby.

Many also were drawn out by the promise of something better in the booming suburbs: relief from small apartments. Expansive back yards, brand-new school buildings, no down payment for veterans. New roads and sewers, financed by the federal government. A perfect place to raise children -- and everyone was having them. The exodus from the city marked a fundamental change in the way Americans viewed the good life and distinguished this country from most others in the world.

But federal mortgage guidelines and the absence of fair-housing laws kept most black people out.

The movement outward from U.S. cities began in the 1930s, but it took off after World War II. Of the nation's 15 largest cities, 10 (all in the East or Midwest) lost population in the 1950s.

In the District, the growing black population was crowded and longing for more space. In 1948, the U.S. Supreme Court granted some relief in ruling that covenants restricting blacks, Jews or others from buying homes could not legally be enforced. A trickle of desegregation followed -- parochial schools in 1950, Hecht's department store in 1952. Then came the 1954 Supreme Court decisions, one striking down segregated schools in most of the country, the other specifically for the District of Columbia.

In a memoir in "Washington History" magazine, Wice remembered the day his school was integrated, "the ring of grim-looking, mostly white parents surrounding the entrance to the school and scattered groups of D.C. police trying to remain unobtrusive as students arrived."

Rudolph Elementary School and MacFarland Junior High, which Wice attended, went from overwhelmingly white in 1954 to overwhelmingly black in 1956. Of nine boys he hung around with, eight moved out.

His neighborhood slid from white to black in three stages, said Wice, who now teaches political science at Drew University in New Jersey. First came a trickle of doctors, lawyers and other upper-middle-class professional blacks who moved into the better houses. Then came some working-class whites, drawn by bargain prices of houses that sellers did not want blacks to buy. Finally, most whites fled, and less-well-off African Americans moved in. To a white middle-class parent, the street corner suddenly looked less friendly.

"People would say, `Be careful -- don't go below Gallatin, or Farragut,' " Wice recalled. "You would be locked into a smaller and smaller area that your parents would let you go into."

Ten blocks from where Wice lived, Joseph Hairston bought a house in 1954, the first black person to do so on that block. A military man, he had intended to buy in Arlington, near his post at Fort Myer, but changed his mind when Virginia officials offered massive resistance to school integration.

He found a house on Kennedy Street NW for himself, his wife and his three daughters. The white sellers "did not give a damn who they sold to as long as they could get out," he said. The wife left the room whenever he came in, so he negotiated terms with the husband.

"The first few nights, the hostility [from neighbors] that I felt was such that I did not move my family in when I settled in the house," said Hairston, 77, who went on to become chief counsel to the Treasury Department before he retired. "I spent the first two nights in the house by myself -- fully armed, just in case."

A white neighbor later confessed to him she had gone to the U.S. attorney to try to block the sale. The hostility eased in time -- it helped, Hairston said, that he fixed up his dilapidated house.

A decade later, he moved to Shepherd Park and joined Neighbors Inc., a group formed in 1957 to promote integrated neighborhoods and counter pressure on whites to leave. He later served as its president.

One of Neighbors Inc.'s founders was Marvin Caplan, a white man who had bought a house in 1957 in Manor Park, north of Petworth. He soon realized he and his family had moved to a racial battlefield.

"The real estate brokers descended on us at once," he wrote in a recently published memoir, "Farther Along." "They aimed their missiles through the mail: letters and postcards, in almost every delivery, offered ready cash for our house. Many nights, sometimes as late as 9 or 10 p.m., the phone would ring and a dealer, in a voice full of sure presumption, would say, `Mr. Caplan? Hi. Due to the changing nature of your neighborhood, wouldn't you like to sell your house?' "

Caplan and others say that some real estate speculators would deliberately try to "bust" a white block by selling to a black family, then publicizing the sale in an effort to panic whites into selling cheap. When confronted about this tactic, he said, the realty companies responded that they simply were providing a public service. (Caplan went on to become executive director of the Leadership Conference on Civil Rights.)

"Playing upon fears of white householders that property values would drop precipitately if a single Negro family settled nearby, speculators bought up whole residential blocks cheap, sold the houses to Negroes at inflated prices, and then repeated the process in another block," wrote Constance Green in "Secret City," her history of race relations in the District.

"Once started, the scheme worked more and more automatically, fanning racial animosities as it spread from one area to the next. And since the cost for Negro purchasers was generally exorbitant, some of them had to let out rooms, overcrowd their dwellings and by thus changing the character of the neighborhood for the worse, feed the anti-Negro propaganda mills."

And it happened fast: In two years, 44 of the 73 homes in one section of Adams Street NW changed hands, mostly from white to black, according to Lusk real estate records cited in the Washington Times Herald in 1953. Normally, there were one or two sales a year in that area.

The flight of whites to the suburbs drew away the middle class -- the people who lobby for better textbooks in the schools or more police on their blocks. Eventually, in the District, the black middle class began moving away, too. Increasingly, the city became the province of the rich who don't need public services and the poor who depend on them. No civic glue held the two together.

Whites still move out of neighborhoods for racial reasons, of course, but social scientists say it happens less quickly and automatically than it did 40 years ago. Attitudes have changed, they say, and civil rights legislation is tougher.

"Whereas before, when change started, people just left, now there is a greater willingness to stay," said William A.V. Clark, a professor of geography at UCLA. "Whites won't enter those changing areas, but they don't necessarily leave as quickly as they had. . . . People are making the distinction: They are willing to live with people of similar socioeconomic standing."

After the war, housing was so tight in the District that Frank Vrataric's landlord could get away with making him buy the furniture in his Benning Road NE apartment for $1,200, a huge sum when he moved in in 1946. He liked the neighbors, but the one-bedroom apartment got crowded when he and his wife had a daughter.

A civilian engineer for the military, Vrataric had heard that Montgomery County was well run, with good schools. The two-bedroom house he had in mind cost $9,500 -- an amount that horrified his father -- but as a veteran, he did not need to put any money down, and the interest rate on the loan was 4 percent.

Vrataric, now 76, knew that his new neighborhood excluded blacks. "I was opposed to segregation," he said, "but that was the name of the game at the time."

The house he bought in Wheaton in 1950 was not finished when he signed the contract for it. When his family moved in, the grass had not come up yet, and the back yard turned to mud when it rained. And yet he recalls feeling overjoyed.

"We were so tickled about getting a house of our own," he said. "It was clean. It was yours."

But it would take a while for others to get used to the new life in the suburbs. After the city's noisy jumble, the streets were so very quiet. Wice, who loved basketball, could not find other boys who wanted to play his city game.

Every weekend, he begged his father to drive him back to his old neighborhood. He knew he could always find a basketball court there, a place he knew he belonged.

"When I was 15, 16, I was in the city more than in the suburbs," he recalled. "It helped me make a smooth transition."

CAPTION: The faces have changed on Rudolph Elementary's playground since Joy Unger and Paul Wice were photographed in 1947.