It’s mid-spring, 1961. In the kitchen of a safe house in Montgomery, Alabama, Dr. Martin Luther King Jr. is tense. In the house with the 32-year-old civil rights leader are 17 students — fresh-faced college kids who, moved by King’s message of racial equality, are literally putting their lives at risk. These are the groundbreaking practitioners of nonviolent civil disobedience known as the Freedom Riders, and over the past two harrowing weeks, as they’ve traveled across the state on integrated buses, their numbers have diminished at every stop in the face of arrests, mob beatings, and even fire-bombings.

Right there along with the Riders, capturing the mood of the movement as it swung between exhilarated and exhausted, thrilled and terrified, was 26-year-old LIFE photographer Paul Schutzer, who covered the landmark “Prayer Pilgrimage for Freedom” in Washington, DC, four years earlier and witnessed firsthand the courage and determination Dr. King inspired in his followers. (Filed along with Schutzer’s Pilgrimage photos in LIFE’s archives are notes from the magazine’s Washington bureau chief, Henry Suydam Jr., observing the passion already swirling around King: “At the end of the ceremonies, a couple of hundred people pressed feverishly on Reverend King — seeking pictures, autographs, handshakes, or just a close look. The jam got so heavy that he had to be escorted to safety by police.”)

Five decades after the Freedom Riders put their lives on the line for dignity and equal rights, LIFE.com presents photos — many that never ran in LIFE — made by Schutzer during that heady era. Here are images that chart the historic journey of King and the nation-changing movement he led, from the monuments of Washington to the streets, churches, and bus depots of the Deep South.