While the practical impact of Brown, which took time to be felt fully (see below), was in some respects significant, the "symbolic quality of the decision," as Yale Kamisar observed in 1969, "was immeasurable," or at any rate substantial. Thurgood Marshall (later, of course, a Supreme Court justice) was the main lawyer for the successful plaintiffs, and the cases consolidated in the Brown decision were the culmination of a long litigation campaign by the NAACP Legal Defense and Education Fund.
Writing in The Atlantic around the time of the 60th anniversary, Ronald Brownstein described Brown's "core mission" as "unfinished" and went on to observe: "...racial and economic isolation remains daunting: One recent study found that three-fourths of African-Americans and two-thirds of Hispanics attend schools where a majority of the students qualify as low-income." Brownstein also noted that the "increasing diversity and shrinking white share of America's youth population" makes more urgent than ever Brown's "broader goal of ensuring all young people the opportunity to develop their talents."
How much and in what ways did the Brown decision matter and, more broadly, how much did the courts in general contribute to the civil rights movement in the U.S.? On the one hand, the prohibition of de jure segregation in the schools was important both symbolically, as already mentioned, and because it did lead, first in the border states and then eventually in the deep South (after years of 'massive resistance' and other forms of obstruction), to some school integration. In 1954, 'dual' (i.e. segregated) school systems were mandated by statute in eleven southern states and six other states, as well as the District of Columbia. The situation in the border states began to change relatively quickly after Brown, but the decision did not have any substantial effect in the deep South until the 1970s, when, as James Patterson (author of a 2001 book about Brown) notes, the decision finally was enforced. Some cities and localities have been success stories of integration -- Raleigh, N.C., to mention one, as discussed in Gerald Grant's 2009 book Hope and Despair in the American City [link].
If that's the glass-half-full side of the story, the glass-half-empty side is that there is overall still a great deal of both economic and racial segregation in U.S. public schools -- there's more segregation now in schools in the North and West than there was 30 years ago. The Supreme Court had a chance to help reverse this trend in 1974 by allowing court-ordered cross-district (urban/suburban) busing in cases of de facto (residential) segregation, but instead a 5-4 majority of the Burger Court went the other way; the case was Milliken v. Bradley. Voluntary urban/suburban integration programs -- which typically do not involve an actual merger of urban and suburban systems, as occurred in Raleigh, but instead move relatively small numbers of students across district lines -- are not an adequate substitute for larger-scale court-ordered programs, but Milliken basically precluded those. Today, according to this piece that aired last month on the PBS NewsHour, there are only eight voluntary urban-suburban 'transfer' programs in the country, involving all together a mere 40,000 students, and almost half of those are in Hartford, Ct. The same piece noted that the number of 'intensely segregated' (i.e., more than 90 percent minority) schools in Rochester, N.Y., has increased fivefold since 1989, and Rochester has one of the voluntary urban-suburban programs.
There is by now a large literature on Brown and on the broader question of the courts and social change, most of which I haven't read (I've listed a few relevant titles at the end of this post, but this list is only the tip of the iceberg). With that said, Mark Tushnet's judgment on the impact of Brown, and of civil rights litigation more generally, seems reasonable, though no judgment here will command universal agreement. In Red, White, and Blue: A Critical Analysis of Constitutional Law (1988), p.132, Tushnet wrote:
Brown galvanized black communities not so much because schools were desegregated -- except in the border states substantial [de jure] segregation continued for more than a decade after Brown -- but because it showed that one branch of the national government was on their side. Two years later the Montgomery bus boycott was the first episode in the development of the modern civil rights movement, whose sit-ins and marches prodded Congress to enact important civil rights acts in 1964, 1965, and 1968. The [Supreme] Court's response to the movement was hesitant and indirect. It never ruled that sit-ins were protected by the Constitution, but it did allow demonstrators to invoke the powers of the federal courts to limit the worst sort of harassment, and it upheld innovative efforts by the executive branch to convict white terrorists under old statutes. Overall the courts played a distinctly subordinate role in the post-1960 struggle for civil rights. It seems fair to wonder whether the pattern of race relations in 1970 or 1980 would have been dramatically different had blacks been forced to use only political methods.Kamisar in 1969 emphasized more strongly Brown's "galvanizing" effect, arguing among other things that it contributed to the subsequent enactment of civil rights legislation and that it sped up or "perhaps even precipitated" the Warren Court's "revolution" in criminal procedure ("The School Desegregation Cases in Retrospect," in the Chelsea House volume listed below, p.xxiv). Probably the only certain statement is that the legacy of Brown will continue to be debated.
References and further reading
Carol Anderson, Eyes Off the Prize
Mary Dudziak, Cold War Civil Rights
Gerald Grant, Hope and Despair in the American City
F. Harris and R. Lieberman, "Racial Inequality after Racism," Foreign Affairs (March/April 2015)
Richard Kluger, Simple Justice
Charles J. Ogletree, Jr., All Deliberate Speed
James T. Patterson, "The Troubled Legacy of Brown v. Board" (pdf)
Gerald Rosenberg, The Hollow Hope
James Ryan, Five Miles Away, A World Apart
Mark Tushnet, Red, White, and Blue
Argument: The Oral Argument Before the Supreme Court in Brown v. Board of Education of Topeka, 1952-55, vol. 1 of the series Oral Arguments Before the Supreme Court (N.Y.: Chelsea House, 1970; paperback reprint, 1983), ed. Leon Friedman, with introductions by Kenneth Clark and Yale Kamisar.
[added later] R. Straus and S. Lemieux, "The Two Browns," New Political Science v.38 (2016)