The young people -- black, white, Asian and Latino -- said they came because they couldn't imagine their lives or classrooms without racial diversity.
The parents and grandparents said they came because they still remember what a segregated society looks like.
Together, thousands strong, they rallied on the sand-colored sidewalks and streets outside the Supreme Court in a chill morning breeze, separated by metal barriers and dozens of police officers from the marble plaza and steps and the facade that proclaims, "Equal Justice Under Law."
There were church groups and labor unions, families and university faculty members, college students from the Ivy League and the Big 10, high school kids from Detroit. They came from as far away as California and Texas, and as close as Georgetown and Howard universities.
While attorneys inside the court argued two affirmative action cases involving white plaintiffs denied admission to the University of Michigan and its law school, the crowd outside chanted, "Jim Crow, hell no!" and, "Two, four, six, eight, we don't want to segregate!"
Then the demonstrators flowed down Constitution Avenue and across the Mall to the Lincoln Memorial, where nearly 40 years ago the Rev. Martin Luther King Jr. dreamed a dream of integration and equality that to many still seems out of reach.
"This is the first march of the new civil rights movement," said Luke Massie, 33, a national organizer with the Coalition to Defend Affirmative Action and Integration and Fight for Equality by Any Means Necessary, which sponsored yesterday's rally. "This is people of all races coming together to move this society forward."
Asante Todd, 23, said he rode 26 hours on a bus from Austin because he believes that college and graduate school must remain accessible to minorities whose families are not well-educated or wealthy.
"After 400 years of slavery, 50 years [of school integration] just doesn't cut it," said Todd, an African American who graduated in December from the University of Texas. "We're not asking for a handout. We're just asking for a possibility."
Many speakers, and those in the crowd, referred repeatedly to the family and alumni connections that helped President Bush gain admission to Yale University as an undergraduate and then Harvard Business School. They also jeered the president -- whose administration argued before the Supreme Court yesterday against the University of Michigan's race-conscious admissions policies -- for framing the war in Iraq as a campaign to bring democracy and opportunity to Iraqis.
"Affirmative Action: Hey, it got Bush into Yale," read one banner held by a contingent from United Steelworkers of Indiana and Illinois.
"The reason we need special treatment is because we had special mistreatment," roared Al Sharpton, an African American civil rights leader from New York City who is seeking the Democratic presidential nomination. "It was against the law for us to go to school. It was against the law for us to read and write. We're not asking the court for favors. We're asking the court to make right what it made wrong."
Patrick Kenney, 22, came to Washington from Boston College with two dozen black, white and Latino classmates.
"It is my fight," said Kenney, who is white, gesturing to his left and his right. "These are all the people I live around, all the people I go to school with, and all the people I hope to work with someday."
Berline Brown rode on one of 60 buses from her Detroit church accompanied by 10 relatives -- two siblings, her husband, a cousin and six children. Asked why, Brown started pointing at the youngsters, pausing when she got to her 6-year-old nephew, D'Andre.
"So our kids will be provided the opportunity to go to any school they want," she said. "To level the playing field."
As the demonstrators marched past First Street and Constitution Avenue NE, two young white men in suits held up signs in their own counter-demonstration. "Affirmative action breeds incompetence," one sign read.
But a white woman standing on the steps of the U.S. Department of Labor building pumped her fist in support of the main demonstrators. And at Constitution and New Jersey Avenue NW, two African American women from the U.S. Bureau of Prisons spent their lunch break watching the main procession and clapping until their hands hurt.
"Represent! Represent!" Randi Thomas, 45, called to the marchers. "I just want to salute you."
The demonstration seemed more homespun than many other political rallies in Washington. There was no stage, or jumbo screen, so it was mostly impossible to see the speakers. The sound system was limited.
But there was a palpable emotion and spirit that peaked at the Lincoln Memorial when participants raised their right fists and sang the spiritual "Lift Ev'ry Voice and Sing," considered the national African American anthem.
Organizers announced at the rally that the event had attracted as many as 50,000 people, but police who monitor such events said the number appeared much smaller. U.S. Capitol Police Chief Terrance W. Gainer put the turnout at about 3,000. Other police agencies declined to release estimates, because doing so has subjected them to criticism by leaders of the groups sponsoring the gatherings.
The group spanned about 10 blocks of Constitution Avenue as its members marched from the Supreme Court to the Mall. Once at the Lincoln Memorial, the crowd filled the steps and much of the area up to the Reflecting Pool.
"Our movement is just beginning," Shanta Driver, national director of the rally organizer By Any Means Necessary, told the crowd. "All things, all movements, start small, and then they grow from there."
Mari Matsuda, 47, a law professor at the Georgetown University Law Center, sat on a barricade and listened, dressed in a black cap and gown. When she was in law school at the University of Hawaii, she recalled, she did not have a single female professor.
"There were opportunities made available to me only because the civil rights movement demanded access for women and people of color," Matsuda said. "I can't do my job as a university professor in a monocultural classroom."
On the steps of the Lincoln Memorial, Kenneth Simmons helped hold a banner from the College of Wooster's Black Student Association, of which he is vice president.
He said he had come to the rally to make his views known and to make history, stirred in part by memories of his grandparents saying they wish they'd been at the memorial for King's speech.
"My grandparents didn't come," he said. "And to the day they died, they wished they had."
Staff writer David A. Fahrenthold contributed to this report.