Washington. -- Four decades after Brown vs. Board of Education, it is a telling fact that two generations of the Brown family -- first Linda, then her children -- have completed their educations in Topeka, Kan., yet the public school system there remains segregated. The original Brown case, in fact, just went through a new trial last month.

That has both symbolic and real-world meaning as the nation on Tuesday marks the 40th anniversary of the Supreme Court's historic desegregation ruling in the Topeka case.

That decision has not ended racial segregation in American education, and it may never do so.

In the Deep South, where the schools were separated by race as a legal mandate and thus were the first targets of the Brown decision, desegregation ran ahead of the rest of the nation for nearly 30 years. But now, even there, resegregation has set in: One major study, issued in December, showed that in 1988, that region's schools began turning back toward more segregation -- the first reversal since the Brown ruling.

In the North, never a prime focus of desegregation efforts, the schools remain heavily divided along race lines. The December study, made by the Harvard Project on School Desegregation, summed up: "For more than a decade, the same four states, Illinois, Michigan, New York and New Jersey, have been at the top of the list of intensely segregated states for African-Americans."

Maryland, according to that report, ranks eighth nationally among the "most segregated states" (just between Alabama and Mississippi). The report said 36.7 percent of Maryland's black students go to schools that are at least 90 percent black -- up 6.4 points since 1980.

Those developments are an enormous disappointment for blacks and for civil rights activists.

But, if they are taken as signs that the Brown decision failed to make a difference, they are misunderstood. The 1954 ruling ignited a social revolution that clearly has not run its course, even if some say it has not yet gone far enough.

Christopher A. Hansen, an American Civil Liberties Union lawyer who in April was back in U.S. District Judge Richard D. Rogers' courtroom in Topeka dealing with the latest round of that first desegregation lawsuit, comments: "I'm very nervous that the Brown case, because we are still working on it, not be seen as a failure."

He adds: "I have very mixed sensations. I am a little depressed that it's 40 years later and I'm still litigating Brown. But you can overreact to that; the overall story is one of giant success. It was a revolution. . . . It has been an enormously powerful experience."

He and others trace all of the modern civil rights gains in some way back to Brown: the broader move toward racial equality in everything from restaurants to jobs to housing, the campaign for equality of the sexes, even the beginnings of a legal sensitivity toward rights for gays. It was "the anchor," says a Washington civil rights lawyer, William L. Taylor.

Mr. Taylor, who is an expert on school desegregation cases, says that the sometimes dismal data about what is happening in the schools 40 years after the Brown decision overlook the "great deal of progress that has been made."

He cites a single statistic, turned up in study done in 1991 by two Stanford University scholars of the results of national standardized testing, showing that "between 1971 and 1991, half of the deficit in educational performance between black and white students was eliminated." This finding, Mr. Taylor says, proves that "getting kids out of racial isolation" gets "real educational results." The Brown decision, he adds, "has produced that much."

Still, he, too, can lapse into pessimism. "I really think progress is now very much stymied, especially in the largest central cities. There is a great deal of racial and socio-economic isolation in the metropolitan areas. And there doesn't seem to be any movement -- in the schools or housing -- to break down those current forms of apartheid."

Pessimism runs even deeper in Gary Orfield, the Harvard professor of education and social policy and the author of the desegregation report that came out last December.

"The country and its schools," he said in that report, "are going through vast changes without any strategy. The civil rights impulse from the 1960s is dead in the water and the ship is floating backward toward the shoals of racial segregation."

It is one of the ironies of the history of the Brown decision and its aftermath that the Supreme Court, which started the civil rights revolution with that ruling in 1954 and then kept it going for years, began to surrender that role as long as 20 years ago.

The case that started it all goes back to Linda Carol Brown's childhood. When she was eight, she lived five blocks away from an elementary school in Topeka. But she caught a bus every school morning and rode 21 blocks to the school that blacks could attend.

The lawsuit that her father, the Rev. Oliver L. Brown, filed in an attempt to open the closest school to Linda was the leading one of the five the Supreme Court decided on May 17, 1954. It took Chief Justice Earl Warren less than 15 minutes to read the entire unanimous opinion, including its footnotes.

In one of the final paragraphs, he read: "We conclude that in the field of public education, the doctrine of 'separate but equal' has no place. Separate educational facilities are inherently unequal."

A year later, on May 31, 1955, the court announced that it was turning over the specific remedies for illegal segregation to the lower courts. It told them to act "with all deliberate speed."

The promise of the two rulings was large, but the resistance to their practical application turned out to be massive.

An early test of wills came in 1957, when Arkansas Gov. Orval Faubus sent the National Guard to keep nine black students from entering Central High School in Little Rock.

The black students got to attend only under the protection of federal troops sent by President Dwight D. Eisenhower. Ultimately, the dispute landed in the Supreme Court, which said sternly in 1958 that no "state support of segregated schools" would be allowed.

The court's patience, however, actually was quite generous. It was not until 1964, a decade after Brown, that the court spoke firmly to school districts that were supposed to be desegregating. Facing a new case from Prince Edward County, Va., one of the districts involved in the 1954 rulings, the court ruled unconstitutional the county's decision to close all public schools rather than let students of different races attend together. "There has been entirely too much deliberation and not enough speed," the court remarked.

A year later, in a Richmond, Va., case the justices bore down harder, saying that "delays in desegregating public school systems are no longer tolerable."

The court's patience was exhausted by 1968. In another Virginia case, from New Kent County, it told school districts that they had a duty to take positive steps to desegregate, to set up systems "without a 'white' school and a 'Negro' school, but just schools. . . . The burden on a school board today is to come forward with a plan that promises realistically to work, and promises realistically to work now." The word "now" was emphasized.

In 1971, turning its attention more to specific steps to desegregate, the court for the first time endorsed crosstown busing as a remedy. It did so in a case from Charlotte, N.C., where a federal judge had ordered 13,000 students bused to desegregated schools. The ruling was written by Chief Justice Warren E. Burger, then in his second year on the court.

The court made its first foray into a school district in the North in a case from Denver in 1973. Even though Colorado had never required school segregation by law, the court found that there was proof that the city schools in Denver were intentionally segregated by local school board actions.

But the next time the court confronted a major case out of the North, a year later, a significant shift came. By a 5-4 vote, in a busing case from Detroit, the court nullified a court-ordered plan to desegregate 54 city and suburban school districts in three counties.

The court laid down the constitutional rule that, if intentional segregation was confined to only one district in a metropolitan area, only that district could be ordered desegregated. Outlying districts that did not keep the races separated on purpose could not be linked with the segregated district to achieve a city-suburbs remedy, Chief Justice Burger wrote for the majority.

Civil rights activists and desegregation experts now blame that 1974 ruling for much of the "central city" school segregation that prevails today. That ruling, says lawyer William Taylor, "just made it difficult to break the boundaries and cross jurisdictional lines" in a way that could break down racial isolation of blacks in the core city.

Through the 1970s, with judges focusing almost entirely on single districts, the list of court-ordered desegregation plans grew longer, even if more limited in scope. Ultimately, more than 1,000 court decrees existed across the nation.

As time went by, however, school districts began pressing to know when they could be free of a federal judge's supervision. Many claimed that they had done all that the courts had required and sought to reclaim full control -- perhaps to end busing and to go back to neighborhood schools.

The Supreme Court in 1986 passed up its first chance to give constitutional guidance on when school districts could be considered "unitary" -- that is, they no longer had any racially identifiable schools, created by official action. But in a pair of rulings, one in 1991, another in 1992, the court declared that school districts could be set free by federal judges if desegregation plans had been followed faithfully for years, and officials no longer made school policy based on race.

So far, more than 100 districts have been set free of court orders, either by direct withdrawal by courts or by unchallenged returns to local control.

During those years, the Brown case itself was taking another turn through the courts. The school district in Topeka was one of those that thought the time had come to get released from judicial oversight. In a 1989 ruling, reaffirmed and broadened in 1992, the 10th U.S. Circuit Court of Appeals said Topeka had not yet done enough.

"The Topeka school district," the Circuit Court said, "has exercised a form of benign neglect. . . . What Topeka did not do is actively strive to dismantle the system that existed."

The Supreme Court, apparently deeply reluctant to be drawn back into the symbolic Brown case, simply let the Circuit Court ruling stand last June, bypassing the school board's appeal. Then, just last month, lawyers for the school board and the challenging parents took part in a 3 1/2 -day trial in Judge Rogers' court, discussing what to do next. "Judge Rogers was not thrilled with either plan" put before him, ACLU lawyer Christopher Hansen noted.

In the meantime, Linda Brown Smith's son and daughter had graduated from high school. Mrs. Smith is now a grandmother; her children's children may be affected by the outcome.

Lyle Denniston covers the Supreme Court and legal issues from the Washington Bureau of The Baltimore Sun.