Looking at the pictures, it is hard to imagine that it happened in America, but it did, and not so long ago: Fifty years ago in Little Rock, Ark., white adults hurled insults and jeers at nine black teenagers who just wanted to go to school.
It was the first test of the Supreme Court decision striking down the separate-but-equal doctrine that had kept schools legally segregated.
In September 1957, the nine black students trying to integrate Little Rock Central High School were repeatedly blocked by the Arkansas National Guard, under orders from the governor.
After weeks of crisis, on Sept. 25, President Eisenhower brought in the U.S. Army -- and the Little Rock Nine, as they came to be called, finally enrolled.
Today, Little Rock Central High School is more than half black and it is one of the best public high schools in the country, sending students each year to the nation's best colleges.
But while there is no longer anger between the races at Central, both teachers and students admit there is not much mixing either.
"I think Central is two schools," said teacher Cynthia Mahomes. "I'm not necessarily saying it is by design, but I think the way it happens, the reality ... is that there are two schools. ... There's a black school and a white school."
Two former Little Rock residents, brothers Brent and Craig Renaud, spent most of last year filming at Central High School. Their film, "Little Rock Central: 50 Years Later," airs Tuesday on HBO.
They found that the division exists in and out of class. Most black students arrive by bus, while the wealthier white students drive. They eat separately at lunch and they often play different sports after school. The golf team last year was all white.
When one of the Little Rock Nine, Minnijean Brown Trickey, returned to the school, she immediately noticed how the classroom she was addressing had divided itself by race. It "disturbs the hell out of me," she told them.
At first, they didn't realize what she was talking about.
ABC News asked students if they felt any racial tension at Central. Both black and white students said they did not.
"Fifty years ago, people sat away from each other because there was hatred, there was ignorance behind it, and today it's much more who am I comfortable with," said Angelica Luster, a Central High School junior.
Principal Nancy Rousseau said it's an uphill struggle to get the students to mix.
"I push them all the time to get out and find out about other kids and other cultures, and they don't necessarily do that," she said. "Kids are too lazy, and it's a problem that we experienced. I've talked to principals all over the United States and it's such a universal problem."
But perhaps more serious than the social separation is the academic segregation that persists at Central. Remedial classes are mostly black. Advanced placement classes are almost all white.
Senior Anne-Elise Hawkins said those who do well choose to do well.
"It doesn't matter if you're black or white or Hispanic or Asian," she said. "You choose how you want to challenge yourself and where you want to go."
But Luster, one of the few black students in AP classes, said success also requires support at home.
"My mother was always there to tell me to read this, do that, do your homework," she said. "And not everybody has that. That's why my situation was different. There's a lot of people who don't have that."
Rousseau said she is trying to close the gap between her black and white students through outreach programs and intensive tutoring, but admitted the problem is bigger than any school can solve.
"You've got kids never had a book read to them," she said, "and they come home from school and their parents are working because they have to put food on the table."
Asked if she will see a time when the AP classes at Central represent the racial mix of the school, Rousseau said, "I think we have a whole lot of work to do in our society before that ever happens."
But Luster, who is struggling to take advantage of the opportunities at Central, is more optimistic.
"Fifty years may sound like a long time, but it's not," she said. "We have such a long way to go, but we have changed so much already."
Dan Harris, Kathleen Hendry and Nils Kongshaug contributed to this report.