The commercials for Greyhound bus company in 1961 paint an idyllic portrait: happy families riding on buses, partaking in beautiful landscapes outside their windows. Slogans set to music extolling the comforts of going Greyhound.

Stanley Nelson uses these advertisements to great effect in his documentary, “Freedom Riders,” a PBS “American Experience” film that debuts at 9 p.m. Monday.

The filmmaker contrasts those images with black and white still photographs showing a very different travel experience for black passengers. Those photographs show black travelers jammed together in the rear of the buses. Inside the terminals, whites only and colored only signs spell out the cruel inequities of the segregated South.

“Freedom Riders” recounts the efforts of more than 400 black and white Americans who in 1961 rode Greyhound and Trailways buses into the deep South to test the enforcement of federal desegregation laws.

The native New Yorker uses never-before-seen footage from that era and interviews with dozens of Freedom Riders, many of whom were college students trained in nonviolent protest techniques. The film traces the riders’ harrowing experiences in Alabama, where they were beaten and jailed; and their time in Mississippi, where state officials jailed more than 300 Freedom Riders for “breach of the peace.”

Meanwhile, their attackers escaped serious prosecution and jail time, despite press footage showing their faces.

The Freedom Riders’ efforts resulted in a ruling by the Interstate Commerce Commission in the fall of 1961 outlawing discrimination in interstate travel.

Nelson’s film is based on the book, “Freedom Riders: 1961 and the Struggle for Racial Justice,” by historian Raymond Arsenault. A 2002 MacArthur Fellow, Nelson’s documentary credits include “Wounded Knee,” the story of the 1973 standoff at the Pine Ridge Reservation; “Jonestown: The Life and Death of People’s Temple,” and “The Murder of Emmett Till.” Emmett was a 14-year-old Chicago boy who was tortured and lynched by white racists after he was accused of whistling at a white woman. The boy was in Money, Miss., visiting relatives for the summer.

Nelson, 59, recently spoke to the AJC about “Freedom Riders.”

Q: How did you come to make this film?

A: I was asked by “American Experience” to look into making it. I immediately said yes, yes, yes! I was really intrigued about making a film about one piece of [the civil rights] movement.

Q: What’s the significance of the Freedom Rides?

A: The Freedom Rides set so many precedents. It was the first time you had this kind of national movement. North and South, young and old and East and West were part of it. [The Freedom Riders movement] pulled the federal government in ... [President John F. Kennedy called in federal troops to protect riders and community members who were trapped inside a Montgomery church with an angry mob.] The whole piece with Martin Luther King Jr. on the phone with Kennedy [from the church basement]. All that made it fascinating and it was a story that would repeat itself.

Q: The Freedom Riders were ordinary people who decided to take action. What was it like to tell their story?

A: They are incredible people. That’s been for me the greatest joy in making this film — being able to screen the film with the Freedom Riders. They always get a standing ovation. For me, I know that I wouldn’t be up on stage as an African-American filmmaker if it were not for their sacrifices. This film moves people in a way that other films I’ve worked on haven’t. It touches everyone.”

Q: What surprised you in making this film?

A: It had so many twists and turns. It showed the worst of America and best of America. The most surprising elements were the national and international ramifications of the Freedom Rides. On one hand, you had the [Freedom Rides] starting with 13 people. On the other hand, you had the Kennedys worried about them as Russia and Cuba were in the headlines.” At the time of the Freedom Rides, President Kennedy was preparing to go to Vienna to meet with Soviet Union leader Nikita Khrushchev. Kennedy was also dealing with conflicts in Cuba.

Q: What’s the film’s lesson?

A: For one, I’d like young people to know their history and see the courage of their forefathers and mothers. Two, change comes if you stand up and make change. Young people haven’t seen it happen. We’re 50 years from the Freedom Rides and 40 years ago from the rest of the civil rights movement. You can be 45 years old and have never seen any of this happen.”

“I wanted [to make] a film that was accessible for young people. These people got on a bus and changed forever those signs that were there for generations —the colored-only signs. They started that movement and started that change.”