The Rev. Martin Luther King Jr. speaks to protesters in Montgomery, Alabama, on March 25, 1965. About 25,000 people had marched there from Selma, Alabama, to protest discriminatory practices -- such as poll taxes and literacy tests -- that prevented many black people from voting in the South. It was the last of three marches that month.
A hearse carries the body of Jimmie Lee Jackson, a black deacon and civil rights activist who was shot by a state trooper during a voting rights march in Marion, Alabama, in February 1965. Jackson's death was a catalyst for the first Selma-Montgomery march.
State troopers swing billy clubs to break up the march on "Bloody Sunday." In the foreground, activist John Lewis is being beaten. He suffered a fractured skull. Lewis is now a US congressman.
Two days after "Bloody Sunday," a second march started in Selma. This time, the crowd turned back at the bridge when it met a barricade of state troopers.
Marchers kneel in prayer after being stopped by state troopers in Selma.
Doctors attend to James Reeb, a white minister from Boston who was attacked by white men for taking part in the demonstrations. He died on March 11, two days after he was beaten.
Protesters sleep on a Selma street on March 11.
US President Lyndon B. Johnson, seen here on March 18, 1965, advised Alabama Gov. George C. Wallace that he would federalize the Alabama National Guard if Wallace were "unable or unwilling" to call out the Guard to protect marchers. The next day, Wallace sent a telegram to Johnson asking for help, saying the state did not have enough troops and could not bear the financial burden of calling up the Guard.
King, center, walks with his wife, Coretta, during the third march on March 21. About 3,200 people marched out of Selma under the protection of federal troops.
Marchers walk past a young white man holding a Confederate battle flag.
Protesters carry American flags during their march to Montgomery.
Marchers walk through mud. The protest had grown to about 25,000 people by the time it reached Montgomery.
Singer Joan Baez, who entertained activists with music before the march, stands in Montgomery on March 25.
Marchers arrive at the Alabama State Capitol in Montgomery. A few months later, President Johnson signed the Voting Rights Act, which ensured that everyone's right to vote would be protected and enforced.