If one were to believe the Hillary Clinton campaign and some some of its backers, Bernie Sanders was a near stranger to the civil rights movement and no activist in the mold of Hillary Rodham.

Yet few who have spent more than 10 minutes watching the passionately serious, unsmiling Sanders campaign on a platform of social justice could imagine him, even 53 years ago while a University of Chicago student, as a typical privileged white kid with not much more on his mind than the next midterm or party.

Sanders’s activist record got a boost this year when a photo surfaced that showed him getting arrested in Chicago during protests in 1963 against the use of so-called “Willis Wagons.” The trailers, named for the despised (in the black community) CPS superintendent, Benjamin Willis, were deployed disproportionately on the South and West Sides as overflow space for African Americans whose segregated schools were overcrowded. Black parents argued that the trailers, typically placed on on schools’ parking lots or playgrounds, were being used to keep black students out of white schools, some of which were underpopulated. In the resulting boycotts, a whopping 200,000 students, mostly African American, stayed home from school.

Gordon Quinn, a founder, in 1966, of Kartemquin films—the studio is best known for “Hoop Dreams” (1994)—shot the protests. Now Quinn, 73, is working on a documentary about the 1963 boycott, which has been largely overlooked in histories of the civil rights movement.

The documentary is scheduled for release in 2017. Quinn had initially hoped to have it out in 2013 for the boycott’s 50th anniversary, but it could turn out that his timing will be asset. The project has been energized by its connection to the real-life drama playing out in this wild campaign season.

I interviewed Quinn, along with a young producer, Rachel Dickson, in Kartemquin’s North Side studio. Here’s an edited and condensed transcript of our conversation, along with a link to photos and video that Kartemquin has gathered in its ongoing research for the documentary.

Tell me about the 1963 boycott.

RD: Gordon actually filmed the boycott in ’63 when he was 21 years old and a student at the University of Chicago. It was a massive boycott, but over the years no one has paid attention to it. It’s not something that’s in the history books. People didn’t know that 200,000 students had boycotted CPS schools because of segregation and inequality.

In doing our research we discovered that Martin Luther King came to Chicago in 1966 specifically because of the boycott. He was really impressed by the organizing and the parents’ role. One of the things we found was audio from WVON radio here. A girl who had participated in the boycott called in questioning whether her actions had made a difference. King patiently listened to her and reassured her that her actions were indeed extremely important.

The year before the ’63 boycott, Bernie Sanders was protesting against segregation at his own university. Tell me about that.

GQ: Six months ago I saw this picture floating around on Facebook of the sit-in at the University of Chicago, where we had caught the university in 1962 discriminating against its own black students in housing that it owned, rental housing. They couldn’t deny it. They said, “Oh, white people, you have to go slow. We’re with you.” We sat in and Bernie Sanders was there. I took the pictures. We marched to the president’s office [George W. Beadle] and sat in the outer office. We were very polite, which looks quaint when you think about 1968 when they occupied the whole building and trashed it.

Footage from ’63 Boycott

This controversy has erupted, all these decades later, about whether Bernie Sanders, desperate to eat into Hillary’s support among African Americans, was really arrested while protesting against discrimination.

RD: One hundred and sixty-nine people had been arrested in the summer of ’63 and four people were charged, and one of them was Bernard Sanders, 21. I put the clip up on Kartemquin’s blog and within a day it was all over social media, getting all these media requests. Our web site went down. Too much traffic. It was in the New York Post, CNN, the New York Times, WGN-TV, the Chicago Tribune. The Tribune went to its archives and found stills. We were shooting film; the Tribune was shooting stills.

GQ: They had a shot of what we thought was Bernie being arrested. We put it on our website. Is this Bernie Sanders? Can you help us? We were looking for someone to confirm.

I read that Bernie was recognized by his wrist watch.

GQ: Yes, the campaign wasn’t saying anything about it. Kind of radio silence for a bit. And finally they acknowledged that, yes, he has looked at it and said that it’s him. And “That’s the watch I wore at the time.”

You started to film the parents protesting the Willis wagons in the summer of ’63. How did that come about?

GQ: Jerry Blumenthal, also a University of Chicago student, who was one of the founding partners of Kartemquin Films [He died in 2014], heard there was going to be this demonstration at 73rd and Lowe in Englewood. The news had leaked that the school board was going to take these kids and put them in a windowless warehouse. And the parents freaked out. All this tension because the black schools were overcrowded, while white schools were underutilized. God forbid you should take these kids and put them in a white school; instead they’re going to put them in this warehouse. That didn’t fly. Then they decided they’re going to build this school on the same site and it’ll be all trailers. They’ll just put four to six trailers together and it’ll be a trailer school.

So the parents are coming out. Every time they try to clear the land, parents are blocking the bulldozers, chaining themselves to things. And there are students supporting them. So [fellow U of C student and Kartemquin cofounder Jerry] Temaner goes out to shoot a roll or two of film. And the guy that he brought with him, our friend, to help him carry things, is Philip Glass [another U of C student]. If you look at some of our early films, they had music by Philip Glass. For like a hundred bucks, “Hey Philip, could you make a little music for this film?” He was just somebody we knew. We knew he was brilliant, but he wasn’t Philip Glass yet.

I grew up in Chicago and went to a North Side CPS school at that time, but this is the first I’ve ever heard of this ’63 boycott.

GQ: I offered it to Eyes on the Prize [PBS’s 1987 14-part series]. I offered it to others who were doing things on the civil rights era; no one really wanted to tell the story of the boycott. It’s mentioned in some books, but we had all this footage. We filmed it. There were four of us. Three of us were students and one was the guy who taught me to shoot, Mike Shay, who was a still photographer who did a lot of work for Ebony. I thought, wow, 200,000 kids staying out of school. That’s a big story. The black community was basically out of school. We have these shots, a few shot through windows, in which you see empty classrooms.

These were parents who got pissed off. Later they became organizers, but this was their first real taste. So we started to find people and interview them.

Of the people you interviewed, who stands out?

GQ: Rosie Simpson. She was a parent organizer.

RD: She worked for 20 years as an organizer for the packing house union.

GQ: And that was one of the things we were really interested in. How did participating in this boycott change your life? How did it change your sense of who you were? We interviewed a terrific woman named Sondra. She is in our footage. She’s a research scientist, a PhD. She talks about being in school and this was at the time they’re putting the trailers behind the schools. She signs up for Latin and the counselor calls her in and says, “You can’t take Latin. It’s a waste of time. You’re going to be a secretary.”She still carried some anger after all these years.

It must be discouraging because in some ways it seems nothing much has changed at CPS.

GQ: Yes, the schools are segregated today; more than ever before. It’s in our film. We have people saying that nothing has gotten any better.

When you release this film next year, how will people find it?

GQ: We hope to get it on PBS, we will for sure show it on WTTW. And then we’ll do a kind of digital on-line release too. We’re not going to make it hard to get. And we’ll use it to drive our website because we want that to be a platform for people who are talking about what’s going on in the schools today.

Back to Bernie. Are you going to vote for him for president?

GQ: I’m for sure going to vote for Bernie because he represents all the things we’re talking about. I think had [Massachusetts senator] Elizabeth Warren run she’d blow Hillary out of the water. For a lot of people Bernie is a tough sell. Not for us. He’s saying all the things we believe in.

Carol Felsenthal is a lifelong Chicagoan and self-proclaimed political junkie. She writes occasionally for Politico Magazine and The Hill. Her books include biographies of Bill Clinton, Katharine Graham, and Alice Roosevelt Longworth. Among her many stories for Chicago are memorable profiles of Michelle Obama and Bruce Rauner. Follow her on Twitter at @csfelsenthal.