In our "Sunday spotlight," an unlikely alliance that made history. Idealistic white volunteers from the north teaming up with those from the south to take on the Jim crow culture 50 years ago this... See More
In our "Sunday spotlight," an unlikely alliance that made history. Idealistic white volunteers from the north teaming up with those from the south to take on the Jim crow culture 50 years ago this summer. They called it freedom summer. Martha Raddatz spoke with the filmmaker Stanley Nelson. Reporter: It was 1964. African-americans had been given the right to vote almost 100 years earlier. Yet fewer than 7% had registered. It was no wonder. You could be fired from your job if you tried to go down and register to vote. If you had a loan, any kind of loan, they would cut your loan. They would publish your name in the paper. Then the registrar would then make you take a test. And inevitably, if you were african-american, you failed. You didn't write anything in there. You didn't pass it. Reporter: Stanley Nelson's new film is a deep and at times unsettling look at the brave women and men who fought for voting rights just 50 years ago. You have your certificate showing you're a registered voter. Reporter: Civil rights organizers in Mississippi had been fighting an uphill battle to register african-americans. We must be stronger than the enemy. Reporter: They needed help from outside the state and looked north. They invited 700 volunteers, mainly white college students. Reporter: Students who had no idea what they would be getting into. One of the things that surprise me, there was tension. Part of the frustration with the organizers was saying this is what it will be like down there. They could see that the kids didn't really understand it. You're going to wind up in jail. I suggest we be a little more serious about this thing. Reporter: But that would quickly and tragically change. They went missing on the first day. Of freedom summer. The very first day. Reporter: On June 21, 196 three young activists, Andrew Goodman and Michael schwerner from New York and James Cheney from Mississippi vanished. The people who understood Mississippi knew they were never going to be found alive. Reporter: The bodies not discovered for six months. Those murders dramatized in the movie "Mississippi burning." It put this kind of shadow over the whole summer. Reporter: For his film, Nelson shares the real-life stories of the once young freedom fighters, who lived in fear every day. They put this noose over my head and attached to a long rope. They jumped back into the car. And I just saw myself being dragged to death. Reporter: It wasn't just intimidation. They were killing people. One of the terms that people always use for what was happening in Mississippi was terrorism. They were being terrorized. Reporter: After freedom summer. After those murders. President Lyndon Johnson signed the voting rights act, which banned discrimination in voter registration. Last year, a sharply divided supreme court struck down a key part of the law. Citing racial progress since freedom summer. Have we gone far enough? I think it's really important to understand the struggle that we had to go through to get people the right to vote. And that probably that struggle is not over. Reporter: For "This week," Martha Raddatz, ABC news, park city, Utah. And now, we honor our fellow Americans who serve and sacrifice. This week, the Pentagon released the names of four Marines killed in Afghanistan. And that is all for us today. Thank you for sharing part of your Sunday with us. Check out "World news" with David Muir tonight. I'll see you next week on "gma."tonight. I'll see you next week on "Gma."
This transcript has been automatically generated and may not be 100% accurate.